The Boveda B49 Instrument For Humidity Control is a replacement packet designed to maintain the optimal humidity level for your guitar or wood instruments. With a size of 70g and a humidity level of 49%, this packet is compatible with both the Guitar and Wood Instruments Kits. It effectively maintains a relative humidity range of 45-55%, ensuring that your instruments are protected from damage caused by excessive dryness or moisture. Trust Boveda for reliable and precise humidity control for your valuable instruments.