These 100% silicone super smooth dildos are designed to fit on most sex machine thrust arms with vac-u-lock attachment systems. The dildo has a small hole in the base for inserting the vac-u-lock male locking piece. It can also be used as a regular dildo without the vac-u-lock attachment. Features: 100% silicone, 19.5cm maximum insertable length, 4.45cm maximum insertable width, 20.3cm overall length, easy to clean, and should be used with water-based lubricant.