The Optimum Series Advanced Silicone Pump Sleeve provides you with maximum comfort! The Sleeve will create a tight seal around your penis. The Pump will stimulate extra blood-flow to your penis. You’ll enjoy better erections and have an improved sexual experience. The Sleeve is versatile enough to fit multiple types of cylinders. The Silicone Pump Sleeve will take your pumping sessions to the next level! This pump sleeve fits cylinders measuring up to 3 inches or 7.5 centimeters in diameter.