Hello everyone. I just wanted to share something that maybe folks on this site already know....but it shocked me. I am at my dad's house for the weekend visiting with my three year old daughter. Well she must have clipped by flashlight bck into my jeans pocket. Well I washed clothes with the flashlight in the jeans. My 4Sevens Preon 2 came out without a scratch and works just fine with not water or dampness at all inside the tube. I guess it really is water proof. :) I love that little pen light.
You say there is no damage ...but wouldn't it be best to make certain that there really is no problems at all .....feel free to send it here and i'll check it out for you :P
This offer goes not just for the preon ....but any lights over 40$ ...
return postage not nessesary
:P
pretty amazing , the washer test is a good one 
. however the dryer test is what separates the LiFos ( LiFePO4 ) from the Li-Ions, j/p
think to verify the "test" going forward we need spin cycle settings and wash temp- seriously i doubt many of my lights would survive.
The light went through a traditional tub washer in hot water and spin cycle and stuff. The light had two Duraloops in it and was on low when I found it in the washer after the machine was done.
A friend of mine (really, it wasn't me :) ) forgot an UltraFire P10-R5 in his trousers and washed it in a washing machine - the same, no damage, no water inside, worked just fine.
The same thing happened with my Zebralight H51f. No problem!
The 4Sevens Preon is probably the best penlight made. Can't believe I don't own one.
maybecuztheycost$50Foy
Should be ok, it's not really a super torture test if you do it a few times.
Even a 9 dollar light can survive
But stuff like for weapon lights, where each light could take like thousands of rounds, each round fired could stress a particular point till the point of failure. PCBs could crack (that's why Jetbeam heads don't have PCBs facing the battery terminals).
haha, good sharing. But it doesn't mean it will be Ok the next time you wash it, good luck.
btw, you remind me to buy battery for my light. 
No problem....it's always good to diversfy and follow-up with multiple tests.