2 - Silica Gel - Hydrosorbent 40 Gram Canisters Desiccant Dehumidifying Drying Unit

These are a nice quality, however, the need "recharging" a LOT...even in a sealed environment with little moisture.

This product does work well as a dehumidifier, but keep in mind that these are the Blue silica gel canisters which contain Cobalt. Cobalt can letch out some sort of poison which is harmful to some collectables like coins, comics and stamps etc. Some studies say in can also cause cancer if you handle cobalt often. I'm not sure you can get cancer from one of these, but why take the chance. Get the NO Cobalt version instead. The No Cobalt version is pretty much the same product but it is orange and not blue, and doesn't contain the poison. I switched out all of these for the No Cobalt version.

Works as expected to keep my guns/ammo dry. All for a great price. I like the cobalt blue as it is easy to see the color change. Am not concerned about the carcinogens as the crystals are packed into the metal holder and cannot be touched directly.

I opened the wrap of one and it was ok....The second canister was covered with huge volume of what looks like a glass or sand powder. These particles are very abrasive so I did not put it in my scope case..( It would be a disaster if some of this powder dropped on my scope or got in touch with the lens) I washed my hands. Now I understand why they are cheap. Next time I will buy from a high quality store with the usual price.