The ALR2 is just 1.67 inches long and 0.74 inches wide, and it weighs 1.05 ounces. It also has a high and low setting; the LED puts out 100 lumens and can run for 2.5 hours on high, and on low, it puts out 5 lumens and can run for 46 hours. Another neat feature of the knife is that it has a magnetic tail, so you can attach it to any ferrous surface.
The Atom AA is powered by AA batteries, and it’s a bit larger than the ALR2; it has an overall length of 2.56 inches and a width of 0.71 inches. The AA also has a magnetic tail and two output settings. On high, it puts out 70 lumens and has a runtime of 3 hours, and on low it puts out 1.5 lumens and has a runtime of 45 hours.
The Atom A0 runs on AAA batteries, and it has a red LED. Red light (as opposed to white) is great because it helps preserve your night vision. On high, the Atom A0 puts out 15 lumens and has a runtime of 5 hours, and on low, it puts out 0.5 lumens and has a runtime of 14 hours. It is 2.20 inches in length, so it’s between the ALR2 and the AA in terms of length. It is 0.50 inches wide and weighs just 0.46 ounces.