Humidity Indicator Card - 3 Dot 30%/40%/50%-50PK

worked well... I added silica gel packs to my military surplus ammo cans and used about an inch of double sided tape to stick one of these to the inside lid of each can... now everytime I open the can I get an instant visual of how well the silica gel packs are holding up and which needs to be replaced.... works perfect and MUCH cheaper than second guessing and having a can of 308 rust up on you...

Works exactly as advertized. I use them in my ammo storage boxes and they provide an excellent indication as to when I need to recharge the desiccant...Plus, these can be brought back to a zero state by heating the card...I just place it close to a bulb and in short order its like new...

Not as good of a quality as my others but they are working, cheaper paper quality

Arrived fast and quality packaged. Seemed like a very nice quality product as well but I can't speak too much to if they work or not as I live in a pretty dry area and only bought them as a "just in case"-type deal.

These things work great in my attic storage bins that I use with desiccant packs. I cut a small rectangle in the sides of the bins, and used clear packing tape as a window. Then I used a small strip of tape to hang the indicator on the inside. Just make sure you don't tape over the whole card, otherwise the indicators will never show the inside humidity! The indicators do return back to blue once the humidity drops below the applicable value, but it does take longer than I expected for this to occur.