HYDROSORBENT® Silica Gel Moisture Absorbers for Camera (40gm - 1 Pack). Blue to Pink. Telescopes, Safe Dehumidifier Rechargeable. Reusable Desiccant Dehumidifier. Made in USA. 40g Mini Canister

I had originally purchased several of the generic version, that says "Reactivate when green" [...] "280 degrees F" on the tin. The beads never really change color on those much, and I don't think they really work very well in the first placeBy contrast, these Hydrosorbent desiccants clearly turn pink when they need to be reactivated. I swapped out the generic ones in all my Pelican cases for these. I was surprised to see that they did their job far better than the generics, by orders of magnitude.In my case, I had a piece of equipment which was used for several hours during an overnight, and thus was exposed to a heavy dew. The following day, after opening the case I noticed a frost / fog inside the LCD display. Apparently the generic desiccant hadn't worked very well. I left the equipment in the sun to dry it out, which worked. I then ordered these Hydrosorbent desiccants to replace the generics, because I didn't have time to reactivate before I needed the same equipment for another overnight.First off, what seemed to be a dry case after an afternoon in the sun obviously wasn't. Lo and behold, the first Hydrosorbent went pink after a few days, before the second overnight. I replaced the first Hydrosorbent with a fresh one. After the second overnight, with similar dew conditions, there was no fog inside the display. That says it all!I don't know whether I should even bother reactivating the generics after this experience, but I definitely won't be buying more. I'm sticking with these.

I purchased a waterproof/fireproof safe to store my valuable documents, however the safe mfg neglected to mention that within a few weeks my items would be hypersaturated from sitting in the safe. After sealing my documents in the safe I opened a few weeks later to notice that all the items were damp and had a dingy smell. I started doing some internet searches and found that many others have had the same issue. I decided to purhcase 2 of these 40 gram silica gel canisters. The items arrived promptly and looked just like the picture a metal canister with a viewing window to see the silica gel inside. I put it in the safe and after a few days the gel had gone from blue to pink. I expected this since one of the pages I read indicated that initally you would have to reactivate the gel often to purge the inital moisture. So I placed canister in oven per the instructions and they turned back to blue. I have only had the gel for a couple weeks but my documents have dried out and I have not noticed the moisture issue. These items are a life saver.

I have a bunch of these things. I use them mostly for moisture protection for firearms, since I live in very humid South Georgia. I have found that these 40 gram units work very well. I check the indicators on them frequently, and find that in summer they will need "recharging" about every two months, in winter only about every four months. This refers to items kept inside an air conditioned house. The recharge is really just drying the silica gel, done in an oven set at 300 degrees for 2-3 hours. No odor, so your wife won't get mad..I stick mine on a cookie sheet and let them bake while I do other chores. Good product, recommended..beware of some on the market that LOOK almost the same as these, but contain less gel, or crummy gel. The knock-offs are usually much lower-priced than these, but are a total rip-off.

Using them in my gun case. I have to re-charge these every few months. They seem to work quite well, though after going shooting on a rainy day, I still encountered some very light rusting the next time I took the gun out.Only caveat: I always have a hard time telling when the color has changed all the way, because I’m red-green colorblind, and the pink isn’t particularly obvious. (Though the pellets start out in a very dark color, I’m never sure whether they’ve turned color all the way yet.)

I was reading the reviews that others wrote and need to clarify a few points. For an ammo can these are perfect! Some when 8 months without changing color. It all depends how much moisture cardboard or material in the can holds... Recharging only takes 3 hours in the oven.Secondly, the plug Eva-dry are great too but for large areas such as a safe. Color changes within a month since its open air and not air tight. Recharging can take anywhere between 8-14 hours and they tell you not to keep it plugged in longer than 16 hours.Hope that's clear enough.

For the price, the 40 grams of silica gel in the nice little metal box is far too few to dehumididy anything but a tiny area, like the size of a breadbox -- just a fraction of the claimed 3 cubic feet. It's a convenient form, but gram for gram, it's price gouging for silica gel. I also can't tell what color the window is, ever, and have to use a moisture indicating strip. I still use it in a firesafe, only with a bunch more loose crystals in an open container.

Even though one of these was damaged, I still use it for absorbing any moisture that might invade the interior of our safe. Hydrosorbent SG40 is a simple aluminum holder filled with Silica Gel and it works. I keep one in the safe and the other elsewhere. When the one in the safe is full or close to full with moisture, I remove it and replace it with the backup. In an effort to maintain even moisture I simply change the canisters about one time a month or no longer than every 6 weeks.

It is very similar to another 40 gram unit I got through Amazon. However this one has different color silica and a longer duration, higher temperature revive routine. That is surprising to me. So far both units seem to perform the same and at this point I would recommend them.

J'en avais acheté plusieurs pour m'assurer de réduire le taux d'humidité dans des étuis à instruments. Je ne peux pas dire si c'était vraiment efficace le fait est que la couleur passait rapidement à la couleur qui indique une saturation en humidité. Je n'ai jamais réussi à les faire sécher pour qu'ils reviennent à la couleur initiale quand ils sont censés être secs. Je suis passé à un autre système de contrôle d'humidité depuis et je n'ai plus ceux là.

Celà fait maintenant 3 ans que j'utilise et ré-utilise ces dispositifs ré-utilisable et je n'ai pas eu de souci. Mes malles à optiques d'appareil photos restent seches et je n'ai pas eu de fungi.

A+++ Fast shipping. Will buy from again. Thank you!