Bosch GLL40-20G Cross Line Laser Review – A Green Light To Cross The Line

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bosch gll40-20g

What's This?This post is sponsored by The Home Depot. A couple of months back, we took a look at Bosch’s fancy-schmancy GLL3-300 laser level. With the ability to shoot one horizontal and two vertical lines simultaneously, and a range of 200’, the Bosch GLL3-300 is aimed at pros doing big jobs. If your jobs aren’t quite so demanding, but you still have the noble goal of having everything level and plumb, the bright green light of the Bosch GLL40-20G Cross Line Self-Leveling Laser might be just the ticket to get squared away – and for a lot less green.
The Bosch GLL40-20G Laser. A lot of green light in a small package.

Roughly the size of a tape measure, the Bosch GLL40-20G Cross Line Laser shoots bright green intersecting horizontal and vertical lines at distances up to 40’. Bosch uses their proprietary VisiMax technology to monitor the laser’s temperature and power consumption, and deliver the brightest line for the job at hand. Using the same self-leveling technology as the GLL3-300, just get the Bosch GLL40-20G within ±4° of plumb and level, and the laser will finish up the task. The laser comes with a soft storage pouch, and a handy little mount that can clamp onto a variety of surfaces. Here’s the full feature and spec list:

• Compact 40 ft. cross-line laser design – features green beams for visibility, self-leveling technology for accuracy and VisiMax for brightness
• VisiMax™ technology – delivers maximum beam brightness, optimized energy efficiency and long-term tool reliability
• Bright green-beam laser lines — up to 4X brighter than standard red beams
• Cross-line mode – projects two bright lines that are precisely level and plumb, for a wide array of leveling and alignment applications
• MM 2 flexible mounting device clamps to multiple surfaces and provides a rotating 360° neck for quick setup and simple fine-tuning
• Smart pendulum system – self-levels and indicates out-of-level condition
• Secure transport – pendulum locks when switched off to help ensure long tool life
• Ergonomic, compact and lightweight – easy to use and easy to store
• Features ¼-20” tripod thread for use with MM 2 mount or tripod
• Self-leveling range: ±4°
• Operating temperature: 41° F / 5° C ~ 104° F / 40° C
• Range: Up to 40’
• Weight: 0.5 lbs.
• Width: 2.3”
• Includes: (1) GLL40-20G Green-Beam Self-Leveling Cross-Line Laser, (1) MM 2 Flexible Mounting Device, (1) Pouch, (2) AA Batteries

bosch gll40-20g
The box has everything you need to start making green lines.

Getting The Bosch GLL40-20G Ready To Cross The Line

Inside the blue box is everything you need to start making lines with the Bosch GLL40-20G. The laser operates on two AA batteries, which are actually included. What a concept! Just pull up the little tab on the back of the laser, pull off the cover, insert the batteries, and click the cover back into place. It latches very securely.

bosch gll40-20g
Twin AA batteries power the green beams…

Operating the Bosch GLL40-20G Cross Line laser is about as straightforward as it gets. Slide the power switch to the ON position, and it turns on. All done? The OFF position powers the laser down, and also engages the pendulum lock, which protects the self-leveling mechanism. The kit includes a soft pouch where you can stow the laser; unfortunately, there’s no room for the included mounting device.

To position the Bosch GLL40-20G, you have several options. It can be set on a table, workbench, or any other relatively level surface. If that doesn’t happen to be quite the height you need, don’t fret. The bottom of the laser is threaded with a ¼-20 female thread, so it can be used with any standard tripod.

Bosch GLL40-20G
The bottom of the Bosch GLL40-20G has a threaded 1/4-20 hole…
Bosch GLL40-20G
And the laser can be mounted on any standard tripod.

Don’t have a tripod, or have a job that requires getting into a tight or weirdly-shaped spot? If there’s a nearby surface that measures between ½” – 2-3/8”, it’s the included MM 2 mounting device to the rescue. Its rubber-padded jaws can clamp onto a horizontal or vertical 2×4, a pipe, a table edge, the rim of a bucket…or whatever’s handy. The MM 2 threads into the mounting hole under the Bosch GLL40-20G, and the bracket can be contorted until the beams are level and plumb.

Bosch GLL40-20G
The Bosch MM 2 bracket will attach to a pipe or scaffold…
Bosch GLL40-20G
Or a 2×4, workbench, or other handy surface.

Making the final adjustments to get those plumb and level lines is simple. Once you have the Bosch GLL40-20G roughly plumb and level, the self-leveling feature finishes the job. If the lines are flashing roughly every three seconds, that means you’re not within the ±4° tolerance needed for the feature to work. Make minor adjustments until the lines stay solid; the system works very well, and I had no trouble quickly shooting plumb and level lines.

Green Lines On The Bosch GLL40-20G – A Bright Idea

Green laser levels, like the Bosch GLL40-20G, are touted as being brighter than red lasers. I’ve used several lasers that project red lines, but never a green-beamer, so I was curious to compare the two.

Bosch GLL40-20G
Ready for the Red vs. Green Laser Smackdown!

I took the Bosch GLL40-20G and Bosch GLL3-300 lasers out to my shop, set them up, and aimed them at the opposite corner, about 35’ away. Both lasers were clearly visible, but the green beam on the Bosch GLL40-20G was definitely easier to spot, even though it was close to the limit of its 40-foot range.

Bosch GLL40-20G
Both lasers are easy to see, but the green is much more visible.

Putting The Bosch GLL40-20G Cross-Line Laser To Work

The Bosch GLL40-20G was put to work on a couple of jobs in our current project house almost immediately after it showed up. Its first mission was to help determine how badly out of level the living room floor was in the roughly 150-year-old house. The answer? VERY badly. These are the types of projects where I hesitate to even let a level near the place.

bosch gll40-20g
Ah, the character and charm of the older home…

Next, it was time to hit the shower. Or at least shoot some lines into it. We were tiling a 42”-square shower, and the trickiest part is maintaining a nice, straight plumb line. You can draw one on the wall, but then you have to be careful not to cover it with mastic, which can be time consuming. With the GLL40-20G, I set the bottom row of tile, and then just projected a plumb line to set the remaining rows. It sped up the job, and we ended up with a perfectly level and plumb tile job.

Bosch GLL40-20G
The laser level projects a line that won’t get covered with mastic…
bosch gll40-20g
And provides a perfect plumb line to set the tiles to.

Final Projections On The Bosch GLL40-20G Cross-Line Laser

A laser level is the perfect tool for jobs like those we used it on. It’s faster and easier than trying to establish two level points and snapping a line, and likely to be more accurate. Other chores where the GLL40-20G would shine include establishing a line for chair rail or crown mold installation, or establishing a plumb line to lay out the position of your top and bottom wall plates when adding a perpendicular wall to an existing wall. It would also be the ideal way to establish a perfectly level line for installing kitchen base or upper cabinets.

In my shop testing, the Bosch GLL40-20G projected a good, wide visible line all the way across the room. The only issue I found with the laser is that when you’re using it over shorter distances, the horizontal line fades a fair bit once you get several feet away from the intersecting lines. The vertical line is fine. My solution is to keep the laser back as far as possible.

bosch gll40-20g
The horizontal line works best from further back.

The Bosch GLL40-20G is aimed at a different market than the much-pricier GLL3-300. While it doesn’t have all the capabilities of the higher-end laser, its ability to display good, bright intersecting lines would make it a useful tool for any handyman, serious DIYer or handy homeowner to have. Its compact size makes it easy to stow and schlep around, and its self-leveling capability is easy and intuitive to use.

Run time on the twin-AA power supply of the Bosch GLL40-20G is very good. Between all the testing I did, and keeping the laser powered up during the entire shower tile job, the laser was probably on for a total of over five hours, all on the original batteries. When the batteries are getting ready to go to that great battery dump in the sky, the beams flash off and on quickly three times. The laser repeats this pattern once a minute until the batteries are dead. If you’re averse to tossing used batteries, the laser will work just as well with rechargeable AA batteries. That way, you can be as green as your laser.

bosch gll40-20g
It IS easy being green.

If you’re keen on keeping your projects plumb and level, beam yourself up a Bosch GLL40-20G Self-Leveling Cross-Line Laser. The tool comes with a one-year warranty, which Bosch will double if you register it within eight weeks of purchase. The Home Depot’s 90-day return policy lets you go green risk-free. And that’s on the level.

Buy the Bosch GLL40-20G Cross Line Laser from the Home Depot:

Buy Now - via Home Depot

I acknowledge that The Home Depot is partnering with Home Fixated in sponsored content. As a part of the sponsorship, Home Fixated is receiving compensation for the purpose of promoting The Home Depot. All expressed opinions and experiences are our own words. This post complies with the Word Of Mouth Marketing Association (WOMMA) Ethics Code and applicable Federal Trade Commission guidelines.

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About Phil

Phil’s path to the pinnacle of success as HomeFixated’s Senior Writer was long and twisted. At various stages of his life, he worked as a framing carpenter, attended motorcycle mechanics school, served as an Army MP, did a hot and itchy stint installing insulation in Phoenix, owned and operated a small contracting firm doing residential renovations, and worked as an employee of a major airline (Motto: We’re not happy ‘til YOU’RE not happy). He is currently semi-retired, but continues to take on little projects, such as the total renovation of an old farmhouse. Yes, he is a slow learner. Future projects include a teardown restoration of his 1965 BMW motorcycle, and designing and building a kick-ass playhouse for his grandsons. Phil loves spending time outdoors, hanging out with family and friends, cool tools, and a cold IPA when beer o'clock rolls around.

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