I don't use a WML anymore. Too much liability, and too much maintenance. It took a single CR123 cell, so I bought 4 rechargeable batteries, and a really good quality charger. I'd keep two on the charger, one in the light, and a spare in my pocket. The batteries would only last about a week. Once you turned the light or laser on and off, once, the battery would be dead in 2 days or less, so I kept a strict regimen of charging batteries & changing them out. I eventually said, "Screw this!" and went to some very reliable $5 Chinese made single AAA battery penlights that started life as bore inspection lights. I keep one clipped on my shirt all the time. It takes a AAA, which are sold anywhere & everywhere. They are just bright enough to identify someone in my postage stamp sized yard, and no brighter. From the "dirty tricks to not get you killed" file: I will carry an old Thyristor SLR film camera flash unit into the yard, along with a flashlight, and the Sig P228R, or a 66-2 in a shoulder holster. If I see someone, and can not ID them, hit him/her with that photo flash, but blink when you hit that button, then move, and use your flashlight. They won't regain their night vision for quite a while. In tactical terms, they are blind as a bat for at least 7 seconds, which is a whole lot of time to make decisions draw, move, shoot, yell, hit, kick, etc. You want the old thyristor & capacitor xenon photo flash that makes a popping noise when it fires, and you can feel the heat coming off of it. I got away from using the weapon mounted light, because I really don't want or need to go to jail for pointing my gun at someone just to use the light. I still use the old photo flash trick. I either have a very angry family member, maybe a drunk neighbor, or a terrified trespasser looking down the barrel of something, when he/she eventually stops seeing spots. I still have the Surefire somewhere. I got a good 10 years use out of it. It takes batteries. It makes the gun larger. It requires drawing & pointing the gun to use the light. Sometimes I will put the light back on the pistol when I travel cross country. I have a super bright Surefire flashlight in the vehicle, the penlights, and ?? guns. I usually plan to stop at a range somewhere along the way, and shoot. Xs 4 $s?