It does not matter as this will not have any effect on the performance of the clamp. If you are circumcised, just place the clamp 1-1.5 cm (1/2 inch) behind the head of the penis.
If you are not circumcised, or have extra loose penile skin, the natural tendency of this loose skin to move down over the head of the penis, so pull any loose skin OVER the penis head and then position the clamp behind the head of the penis 1-1.5 cm (½ inch). This will prevent the loose skin from moving further down the penis causing the clamp to fall off. Full instructions are included with each Dribblestop Kit.