The Extreme-Neoprene Patented Joint Protective Reflective Pet Sleeves are composed of lightly flexible Neoprene. These Pet Sleeves are perfect for all pets in operation recovery and further help prevent joint operation. These sleeves are designed and engineered to place less stress on your pets knee joints and are essential for all older dogs, puppies and even cats. Features Surroundable Reflective Lining for added protection during night walk and are perfect for those active dogs. Features Velcro closures for easy On and Off access. Comes as a set of 4. MEASUREMENTS - SM - 7.48"L x 4"W x 0.125"H MD - 8.9"L x 4.5"W x 0.125"H LG - 8.75"L x 5.75"W x 0.125"H