Some wood cases have twice as much wood as a guitar does. The wood and other internal materials composing the case must be humidified, so it doesn't rob moisture meant for your instrument. Use these Boveda to: Season an empty wood guitar case–one time is all that's needed Automatically, safely and precisely "fill up" the cell structure of a case's wood with moisture Achieve 50% relative humidity (RH) Make subsequent Boveda packs work most efficiently to humidify a guitar This 4-pack seasons one wood case for an: Acoustic guitar Electric guitar Electric bass NOTE: Case seasoning is NOT required: If your case is made of synthetic material If you store a guitar in a gig bag If you store a guitar in a wood case in a high-humidity climate