Get ready for larger, thicker erections with Rock Solid's Auto Pump. This single-speed clear pump allows you to see your growth as it happens. Requires two AAA batteries, not included.Features Creates Thicker, Harder Erections Clear Vacuum Cylinder with Centimeter Markings to Track Progress Soft Silicone Sleeve for Airtight Seal Air Release Button for Fast, Safe Removal Pressure Meter Gauge to Track Results Phthalate-Free, Body-Safe Dimensions Total Length: 10.75 in. (27.3 cm) Insertable Length: 7 in. (17.8 cm) Unstretched Inner Diameter: 3.07 in. (78 mm) Circumference: 7.75 in. (19.7 cm)