Stiff & StrongStiff & strong! There is definitely a reason why they've called this machine "Stiff & Strong", as that is exactly what it does to the penis. The pump is easy to use, creating a vacuum via a pistol grip pump to adjust the pressure according to need. Complete length of cylinder 22 cm (with measuring scale). Insertion depth 21 cm, inner 5. 7 cm, outer 6 cm. of sleeve opening 2. 3 cm (flexible). Material: ABS, silicone, metal.