The Robojac Piston Dildo attaches to either Robojac or Robojil port and can be used for anal or vaginal massage. Now one machine really does do it all. Use the Robojac SUCTION and STROKE controls to set the depth of thrust and amount of withdraw. The Robojac Piston Dildo features a unisex jock-type harness which is quick and easy to put on and adjust. The Robojac Piston Dildo is molded out of highest the quality materials is approx. 1-1/2 inches in diameter is about 7 inches long and has a length of stroke of about 4 inches.