I have a Glo-toob FX (7-Function)(amber), and can testify to their waterproofness. I use it primarily for marking my bag when I cave/camp, and they're as tough as nails...here it is in lay terms...the electrical parts are basically "dipped" in a solid plastic resin, and the machined down to proper size, so as long as the one cap stays on, it's virtually indestrucible. they're not the brightest thing on the planet, but are perfect in dark enviroments. The only problem I had was the battery that came with it had a "paper" top, so it was annoying trying top change the functions, but once I replaced it with a duracell with the plastic top, it worked like a charm. A great light, and I can't wait to get a few more in different colors. Hope this helps!