DR-HO'S Large Flex Tone Gel Pads are compatible with all DR-HO'S Pain Therapy Systems. There are 2 pairs in a pack. All gel pads are hypoallergenic, and can last 70-100 uses. These Electrode Gel Pads are cloth-backed so they can form to your muscles and stick firmly during use. Simply apply water to activate stickiness. Flex Tone Pads can be used on large muscle groups such as the lower back, shoulders, rotator cuff, hip, legs and treating sciatic pain. 2 Pairs (4 pieces) per pack.