Boveda Musical Instrument 2-Way Humidty Control Starter Kit, Small Boveda Humidty Control System automatically maintains a relative humidity between 45-55 percent, eliminating the need for hoses, sponges, or adding water. Simply place a Boveda packet in saddlebag, place in the case and close your case. Boveda does the rest, keeping your instrument at a constant relative humidity between 45-55 percent while it's in its case. Help maintain wooden instruments by preventing warping, cracking, buzzing, shrinking, and expansion. Kit Includes 2 Boveda 49 Percent RH Packets 1 Cloth Boveda Holder Works with Guitar/Bass, Violin/Viola, Ukulele/Mandolin, Clarinet, and more.