Dynamic Stabilizer Ball Base Thermometer Volume Rocker Switch Ships via truck Volume Rocker Switch 6 Standard 140 degree * Measures the range of motion of metacarpal phalangeal and interphalangeal joints * Head has two opposing scales marked in 6 degree increments * Features a linear scale in both inches and centimeters on arm * 5 diameter and fits a 45 55 65 and 75 cm exercise ball * Use base to stabilize exercise ball and prevent ball from rolling around gym * Use base with band or tubing for dynamic workout * Base has 4 built in anchors and 2 grooves for exercise band and tubing * Lightweight portable gym ball base measures 19