Often, when I open a new piece of kit, a sachet of silica gel drops out (the last example was in a tripod!). Now, I know the idea is to keep things dry, but..... When I used to work in a lab, and we had to keep samples dry, usually, under vacuum, the gel might perform for a few days and then need to be dried out for re-use. I find it hard to believe that these little sachets in camera gear do any good whatsoever. Or does someone know differently?