Stretto® Humidifier for Violin or Viola

I recently purchased a new Bam violin case and the store recommended a Bovida humidifier bag instead of the Stretto system which I have always used. After 4 weeks in dry November northeast conditions with the Bovida bag, the humidity in my new case was reading at a low 42%. I understand the acceptable humidity range is 40% to 60%. I switched out the Bovida for the Stretto system and now the humidity is ranging at an average of 53%.

"Put it simple, it works as it claims. I also live in the Chicago area and winter weather here can be hectic. The stretto humidifier manages to maintain the RH of my violin case at about 60 when closed.
I also use distilled water. The instruction says 3 minutes of soaking, but I usually soak the pack for 10 minutes. A gallon bottle of distilled water )about US$0.80( will be more than enough for the whole winter.
The provided velcro does not stick to the interior lining of my case. Turns out I ventured to use the iron-on velcro for clothing )available @ Walmart for about US$4.00(and it works very well. Since I have no access to the back of the material, I simply place a terry-cloth towel on top of the velcro and iron the velcro with steam on."

I have been using the Stretto Humidifier for three years now and am happy to say that it is a very effective product in the battle with wintertime humidity. Living in Chicago and traveling frequently to NYC and abroad, my viola is subject to a wide spectrum of humidity levels, which can not only cause cracks, but can also contribute to a worsening of sound quality during these months.
The reusable insert in the humidifier is dunked in a glass of distilled water (not tap water, unless you are looking for a science experiment the next time you open your case) for ten minutes. The insert should then be patted dry with a paper towel to remove excess water. I have never had an issue of water seeping out of the insert and into my case.
I would recommend purchasing a humidity gauge (I use the Planet Waves Humidity Sensor, also offered by Shar) to keep an eye on your levels. During dry weather, check the insert frequently. I have found that the insert takes on water more easily when not completely dried out.
As far as mounting the humidifier in your violin/viola case, keep it clear of contact with your instrument.

This is an ideal humidifier for my needs. I play and teach violin and viola and have one for each of my instruments. Very effective and will not leak if you follow the directions and don't squeeze the gel pouch. I'm always amazed at how much water the gel absorbs. It can be a bit of an adventure to find just the right spot in your case to install the clam shell and it does have to be directly adhered to the velvet or silk lining of the interior. But making sure my instruments are properly humidified is more important than the interior aesthetics of my case. And the gel packs can be reused several times over - it's best not to let them dry completely to a crisp before re-soaking. Although they will plump back good as new, it just takes much longer than normal. I recommend this humidifier to all my students and colleagues.

This humidifier is well-designed. There are two humidifying bags included. When the ambient humidity is 20%, the tested humidity inside my viola case with this humidifier after 12 hours is about 50%. The result is acceptable, but note that if you open you case frequently, the in-case humidity would be only about 40%, which is still kinda low. So in my opinion, it'll be better if you also use an hudifier in your room.