These are high-end nipple clamps, indicating their attractive styling, and incredibly precise adjustment. They are made mostly of solid brass giving them an attractive gold color. The tension on these clamps is adjusted by turning the black cylinder at the base of the clamp to slowly increase or decrease the pressure. This mechanism allows for very precise, controlled tuning of the intensity. The look, feel and function of these clamps are all top quality and they are prized by those who have had a chance to work with them.