i have used the lasermax in my glock and found it would turn on from slight grazes in the holster or just shooting it would turn on, which is cool for a quick selfdefense reason but plinking during the day it would turn on and waste the batteries. I liked it. it did not change the function but the batteries would wear out quick, and I was stuck with the spring that came on the lasermax. I have not used the crimson one yet and that will be my next laser buy.