The Stamina Training Unit Fleshlight has a canal diameter of 0.5 inches (1.27cm) and is thus relatively tight. The inner surface which is about 9 inches (22.8 cm) is covered by numerous large-sized bumps that protrude deep into the canal. The bumps are positioned very close to one another, forming a highly dense texture that runs throughout the entire canal. This dense bumpy texture applies intense stimulation on the penis accompanied by a strong suction effect. This intense stimulation leads you, during continuous movement inside the canal, to a powerful orgasm within a few minutes. In order to delay the orgasm, you inevitably have to take a short break or to vary the speed of stroking. This is exactly the skill that you can improve by practicing with the Stamina Training Unit because the control over your own sexual arousal and personal stimulation threshold is the key for improving your sexual stamina!