FENDER The Worlds Best Musical Instrument Manufacturer has teamed with the Worlds Best Callus Builder and Finger Strengthener to bring Musicians the best licensed product to help Musicians enhance their playing experience Designed in the shape of Fenders World Famous Stratocaster Guitar RAISED RIDGES The only Finger Exerciser with raised ridges to simulate strings on your stringed instrument HELPS BUILD FINGER CALLUSES A callus is an area of thickened skin that forms as a response to repeated friction pressure or other irritation The Fender Callus Builder is designed to create pressure similar to the strings on a stringed instrument SIMULATE EXACT ANGLE FOR PLAYING It is easy to maneuver the Fender Callus Builder to get the exact angle used while playing your stringed instrument HIGH TENSION Two different resistant levels available RED 8lb and BLACK 15lb The 15lb tension is extremely hard and offers a higher tension than any other finger exerciser on the market