Unique hourglass shape grip tighter int he middle where you want it most when stretching, but with a soft grip. The ends are thicker wont dig or pinch. Inside are two thin raised rings that keep this stretcher where you put it. SQUEEZE is made from FLEX TPR so its lightweight and compact but still packs a punch. Unlike silicone, FLEX TPR has a completely different feel for an entirely new stretchin sensation.Size Height. 2 inches to 5.08 cm Outside Circumference. 5.5 to 6 Inches to 14.02 to 15.24 cm Inside Circumference. 3.5 Inches to 8.89 cm