Now you can order a protective Boveda fabric holder separately if you buy Boveda in bulk for electric guitars or basses, violins, violas, mandolins, ukuleles, banjoes, clarinets and small cases. Musicians who play multiple wooden instruments?or need a little extra Boveda in a case?buy Boveda fabric holders a la carte. So do orchestral retailers and repair shops to thank and educate musicians by including Boveda 2-way humidity control in with recently repaired or new fretted, bowed and wood woodwinds. The polyester exterior of this holder is soft, like a polishing cloth, so it?s safe to store with an instrument. A leak-proof layer is extruded directly to the holder?s interior. This special lining allows Boveda?s pure water vapor to flow in and out to achieve and maintain a constant relative humidity (RH) range of 45% to 55%?the safe zone for wood instruments. (You can also use this fabric holder with High Absorbency Boveda for wooden instruments in high-humidity climates.) Note: ALWAYS insert Boveda into a sleeve of a Boveda fabric holder before placing in an instrument case. Do not mix different Boveda RH levels within the same instrument case. And do not use Boveda in the same case with other humidification products because they will fight against each other and reduce the efficiency of Boveda.