Designed to provide humidity for up to 50 cigars, Xikar’s Crystal 50 Humidifier is activated when you fill it with propylene glycol (PG). The crystals inside the bar will shrink slowly as water evaporates over time. Simply refill the bar with propylene glycol solution to recharge the humidifier for a slow, steady release of constant humidity of 70%. This smaller humidifier is great for travel humidors and cases.