These Mandolin Practice Sheets are in PDF format and cover the keys of C, G, D, A and E. These sheets provide a "drill" sheet that players can use to build up playing dexterity. I find it beneficial to practice chord shapes (especially the minor chords) and scales outside the scope of learning a tune. A mando workout or warm up so to speak. These sheets also provide a reference sheet to building solos or breaks. With the information right there for a specific key, the player doesn't have to have a pile of books or other material in front of them.