Review on 🌬️ Xikar Crystal Humidifier - Long-lasting, Up to 90 Days, Expanding Crystals, Optimal 70% Humidity, 4 oz Jar by Karen Turner

They recommend using Propylene Glycol as the water can easily contain bacteria that will ruin your entire collection. This is a great way to convey the humidity in your humidor. I have a small shoebox size Thompson Cigar. I think I fill it out every 2-3 months, including a check-up once a week. Definitely recommend. The black grid is a bit tricky to put on, but luckily I don't have to fill it in too often. The grid is good, if you hit it nothing falls out.