BOVEDA https://www.amazon.com/s/ref=nb_sb_...ck&sprefix=boveda+,aps,590&crid=2QI5A6CJP7IIP Here's a great bit of information --buy them in a multi-pack. These Boveda packs will last up to 2 years sealed inside the Ziplock they arrive inside. Also, you can use more than one, you can use as many as you like inside your humidor, it won't change the RH. The only difference between using one 60 gram pack and three is that they will last longer with three, that's it. I am currently converting my large humidor over to Boveda, where I had previously only used them in my small humidor. If your humidor is already seasoned, it's simple to do because you just buy the Boveda RH pack you want, no need to go higher 5% to make up for variations due to seasoning the humidor. I suggest getting the 60 gram packs only and skipping the smaller ones, but that's up to you to decide. I use the 60 gram packs in small humidors with no issues at all. Just pop them in, forget it. Perfect RH every time. These last a pretty long time, several months or more. Side-by-side comparison of the two hygrometers at different levels. This is the type of humidification we can expect from Boveda, it's great. You see the Boveda pack on the top tray, and two more on the second tray. Adding more will not increase your RH with Boveda. I now have room to add more cigars, too. No more fighting to get just the right RH on every level of the humidor/cooler. The 60 gram pack works great even in this little humidor. I use 65% RH standard in pre-seasoned humidors. I did use a 10 gram pack previously, and it performed superbly, but this 60 gram should last a bit longer. Excellent.