Black Mini Dehumidifier by GERO Rechargeable Renewable Small Moisture Eliminator JR for Bathroom Bedroom Laundry Room Kitchen Cabinet Gun Safe Pantry and More! Prevent Mold Mildew & Musty Odors-2PK

I've been using Eva-Dry E-500 desiccant dehumidifiers in my gun and ammo safes for quite some time now. I'm a big fan of the Eva-Dry units, but I needed a couple of more units so I thought I'd give the GERO units a try. These particular GERO units are equivalent to the Eva-Dry E-333, in that they're rated for 340 cu ft of air volume.The units seem to be very well made and they're quite heavy, indicating they're densely packed with silica gel desiccant. These use a separate, detachable cord in place of the Eva-Dry fold-out power plug. I think there are pros and cons to each design. The Eva-Dry plug, being inline with the long dimension of the unit, takes up nearly all of a conventional power strip. That's a hassle. The detachable power cord of the GERO solves that problem, but introduces the hassle of having to keep track of the cord. In my case, I have a dedicated power strip near the gun safe for recharging, so I just leave the cord plugged in there. It's something to consider though. The units will quickly become useless if you lose the cords. The cord isn't proprietary, though, so you probably have something else that uses the same two-prong connector.A single one of these seems to last about a week in my gun safe – about the same duration as the Eva-Dry. The moisture indicating window gives a very clear indication of the need to recharge, and recharging was complete in about 10 hours. Interestingly, the outside of the GERO unit does not get as hot to the touch as the Eva-Dry during recharge. In fact, except for the eventual restoration of the "dry" color in the window, it's difficult to know that the recharge is working.One definite downside to these units is the packaging. The Eva-Dry units come sealed in air-tight plastic inside a blister-pack package. While I hate blister-packs, which require a knife to open, the fact that they're sealed during shipment and storage means they're good to go immediately upon receipt. Not so with the GERO units. They ship in a cardboard box, which is terrific, but, inside the box, the unit is packed in an open-ended plastic bag. This requires you to recharge the units for 12 hours before first use. That is just stupid, and is the reason for four stars instead of five.SETTING EXPECTATIONS: Some of the reviewers here seem confused about the nature of these dehumidifiers and how to use them. This may be because the detachable cord gives the impression that the cord needs to be plugged in during use. It does not and, in fact, MUST NOT be plugged in during use. These are desiccant "dehumidifiers". They contain silica gel that absorbs water molecules in the crystalline structure of the silica. The silica is doped with a moisture-indicating chemical to indicate when the silica is reaching it's capacity. At that point, the unit needs to be removed from the space you're trying to dehumidify and plugged in to power so an internal heater can heat the gel to 250F, allowing the moisture to "boil off". After 12-18 hours, the units are recharged and can be used again.The necessity to recharge for 12 hours requires more than one unit per space, so you can have at least one unit working while the other recharges. If you take that into account, these work very well, especially in confined spaces like safes, closets and storage containers. For larger, open spaces, or applications where you won't me around to monitor and recharge the desiccant, a desiccant dehumidifier may not be the most efficient option. Consider an active, condensing type dehumidifier or air conditioning unit for those applications.All in all, I like the GERO units. I'm on the page now to order two more. I'm not sure I like them better than the Eva-Drys, but the smaller physical size is better for my current application.

Item set was initially bought to dehumidify a small bathroom of a family member and a closet. When I charged this item up , I noticed the crystals in the view pane remained pink and the unit itself was cool to the touch. Thinking it was just a problem in the cable I used a substitute cable from another unit that I knew worked. Nothing happened, the unit remained cool to the touch. This set was returned. A similar set I bought from this company worked fine. After I plugged in the units they would be very warm to the touch. And after several hours, the pink crystals would turn a cobalt blue to show it was ready to use.

I am using them to keep my 3D filament dry. I like the window and the color-changing beads to tell me when to re-charge them. The removable external AC cord is great. When the beads turn pink, I plug the units in to re-charge them and they are ready before the end of the day.**ADDITIONAL COMMENT 27 JAN 2017**The original units are still working well. I ordered a second set for a third container of 3D filament and a spare. No issues with keeping the filament dry and working well in my 3D printers.

I'm impressed. I use hot towels for my massage therapy practice, 4-6 per session, and I have a drying rack for them in the office. I needed to do something about the stagnant moisture that was noticeable upon entry, so I bought a 2-pack of these dehumidifiers. The technology is beyond me--super absorbent beads that change colors as they accumulate moisture and release the moisture when charged with electricity--but it works. My office smells (and feels) fine again, and I'm no longer concerned about mold becoming an issue.

I bought this to put in a small gun cabinet, when I got the unit the beads were pink, so after 15 hours on the charger the beads were nice and dark blue. So I put the unit in the cabinet and when I checked it three days later the beads were pink, so back on the charger after about 15 hours blue again checked it again three days later in the gun cabinet back to pink. So two to three days is the max life before needing to be plugged in. Oh and I live in Arizona hardly no humidity!

These work great. I have three all together and rotate them out of my gun safe. They are easy enough to use and I'm happy with them

Works wonders for keeping the dampness at bay. So easy to "recharge"

This is a great item with a great price. I picked this item being it is self contained for regeneration. We will see how unit will work in the future. The price figured out 2 for 1.