The Original Index Knobber® II massage tool is a simple device designed to let you apply deep pressure to muscles within easy reach of your hand. It the ideal instrument for clinic or home use allowing for firm, sustained pressure on targeted muscle. It is as safe and effective as massaging a sore muscle with your own knuckle or thumb. It's unique patented design allows it to be used in several hand positions and by the right or left hands comfortably and interchangeably. Dimensions: 4 x 2 x 1" The Original Backnobber®II massage tool is constructed of durable, fiberglass reinforced nylon and carries a full, satisfaction guarantee. The Backnobber II is used by hooking one of its curves over a shoulder or under an arm and using its leverage to apply firm, deep pressure to knots in the muscles of the neck, shoulder, upper and lower back and to nearly any other location where muscle soreness may occur. Dimensions: 10 x 20 x 1" Colors may vary