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.FeaturesCreates Thicker, Harder ErectionsClear Vacuum Cylinder with Centimeter Markings to Track ProgressSoft Silicone Sleeve for Airtight SealAir Release Button for Fast, Safe RemovalPressure Meter Gauge to Track ResultsPhthalate-Free, Body-SafeDimensionsTotal 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)