Not only is silica common in all those electronics, but it is recyclable,
too. When they are worn out, you can put them in an ovenwear container and
stick them in the oven (after you take them out of their little celo
bag). The indication of silica unable to do its job is that it turns
pink. When its clear again, it can be removed from the oven and sewn back
into little bags.

DW