The water-based power of this pump is for users measuring 7 to 9 inches when erect and can help create harder, longer-lasting erections. Once filled with warm water, the pump seals against the body. For best results start with 3 five minute sessions per use. 1 to 3 months. Also available in clear and blue. Penis sizes 7 inches to 9 inches when erect. Internal length 11.5 inches.