You control the pressure until desired effect with the EZ squeeze handle with pressure release valve.
Features: 
Material: Silicone (Soft Base & Hose), Polystyrene (Clear chamber), ABS (Gauge, Pump, Remote & Bullet) 
Size:  11.75b  (Total length),  2.5b  to 2.6b  (Cylinder diameter at base), 7.87 (Insertable length)
2 AA batteries