Dynarex Cold Hot Medicated Patches contain 5% menthol to relieve minor aches and pains associated with arthritis, strains, bruises, and backaches. The cooling feeling starts right upon application for immediate pain relief. The patch then provides warmth to soothe and relax muscles. The medication relieves pain for up to 8 hours. The patch design is more convenient and less messy than traditional creams. These pain relief patches are self-adhering and conform to body contours. This product is available in two sizes. The 3.2" x 4.7" size is great for the arm or neck and the larger 3.9" x 7.9" size is ideal for the back.