Product Description Simply open the harness, place the pet's front legs through the opening and snap closed. Has two D-rings for added security while walking your pet. The larger sizes have an underside adjustment. XSmall adjusts from 11 in. to 16 in., Small adjusts from 14 in. to 16 in., Medium adjusts from 18 in. to 28 in., Large adjusts from 22 in. to 33 in., XLarge adjusts from 27 in. to 42 in..