Funny I have a whole bunch of SF clicks and I have never had a single one fail.
In fact i have found them to be quite robust. As was posted earlier in the thread Surefire will replace a failed switch very easily.
BTW I now own 4 KL4 flashlights one is a factory L4 the others I bought as heads only. I love them all but I have gone through a fair number of them to get ones I like. One has a terrible defect in the reflector but the tint is great and the defect doesn't impact the beam at all.
A while back I worked very hard to find 2 matching kl4 heads. A difficult task.
One thing I find amazing is just that it seems that no two are exactly alike.
I recently received a kl4 from a member who went through something like 10 of them before he found the one he considers to be "perfect" no doughnut and a perfect tint. Think about it. Going through $1000.00 worth of lights to find the perfect head. This light is mounted on a vital gear single cell body is now my secondary EDc light. It is very white and bright with the smooth wall of light the kl4 is famous for.
In any event the L4 or KL4 is a wonderful piece. I own 4 now I wonder how many I will end up with.... Who knows.
A matched pair:
Yaesumofo