49% Two-Way Humidity Control Packs for Music Instruments – 4 Pack – Standard Size – Prevents Warping & Cracking for Wooden Instruments– Humidifier Packs for Instrument Cases – Resealable Bag

I've been using these for at least 15 years, one inside the guitar (16 archtops) and one in the case. During that time only 3 packs have ‘leaked’, showing damp patches. But there have been two other situations. The first when a pack was resting against a tuner, for about a month or two, it took the finish off down to the base metal, unfortunately a gold Kluson on a Gibson Citation, try and find a replacement. The second was with a guitar shipped to the UK from California with me to follow in 3 months, which actually turned out to be 15 months. The guitars tuners were badly tarnished, Gold Klusons on a Gibson Super V Prototype. I still use Boveda packs but am now more aware of their drawbacks. Don't place a pack directly against metal parts, and be sure to open the case occasionally, to release any fumes that may accumulate if a guitar is stored for an extended period. You can also drop one inside a guitar, as I do, but be sure you have a way to get it out. Best of all control the humidify of your room, though with the English climate it’s easier said than done. But In this way you can probably get along without using any of these expensive packs.

It doesn’t work. I’ve left it in the guitar case for a week and monitored it for a few hours via the app, but the humidity didn’t drop to 49%. It was still at around 60%. Maybe it does not work or it takes a long time to start working

Slightly dissapointing compared to similar products I have used. Used to maintain humidity in instrument cases for fine wooden instruments. The cases are sealed fibreglass cases and although it seemed to maintain a constant of 57% it is not the ideal humidity for the instrument and is not the humidity advertised by the product. Other than that nice design good packaging etc, in future I would look to try other alternatives

According to the humidity meter I bought along with these bags, my case started at 65% and hasn't changed!

Disappointed I bought this and the recommended saddlebag holder expecting it to lower humidity to around 49%rh as claimed. I placed my Gibson guitar in its hard case along with a hygrometer that I bought at the same time, this measures rh as well as records the lowest and highest relative humidity. After four days in the case, unopened, I opened the case up to use the guitar to see that the highest rh was the 63% which was the time when I'd closed the case four days earlier. The lowest, which was the reading when I opened the case was 59%rh. This falls well short of the claimed 49% rh performance. I'm only pleased that I didn't buy the 12 pack! I certainly would not recommend this to my many musical friends - just the opposite, in fact! I take care to write a factual record of how an item performs, if this is useful to you I'd appreciate it if you'd take a second to click the 'helpful' button 🙂