You can also use dry rice. Rice might attract animals.
andyalder
Lots of things come with silica gel sachets, they can be reused if you bake them in the oven at 120C for an hour or so to drive the moisture out.
My shoes came with silica gel - it said "do not eat" on the bag so I ate the shoes instead as it didn't say "do not eat" on them.
Robert
Like others said silica packets will absorb moisture but if your boxes are not air tight boxes you will need to continually re-dry the silica packets as they only absorb so much before they quit working.