Includes: 1 set of 4 replacement pads for use with ReVive Back Pain Relief Belt. All ReVive replacement pads and accessories are manufactured to medical grade standard. It is recommended that you replace your pads after 20-30 sessions. The length of time the pads can last depends on a number of factors including your skin type, frequency of use, how the pads are stored etc. Save the plastic covers on the top of the Gel Pads. After use, put the plastic covers back on the top of the pads to protect them from dust and to retain moisture.