Steel Ball Head Ring from Master Series. This steel ball head ring rests on the underside of the head, just above the shaft, stimulating one of the most reactive areas of the penis. By simply placing the ring around the penis head and placing the ball on the underside of the shaft, it will add light pressure and increased sensation. It can also stimulate your partner during penetration, allowing for distinct pleasure and maximum intensity. Measurements: 1.25 inches inner diameter. Material: Steel.