This smooth plastic 1-1/2" glide cap will protect your patio furniture from any damage because of some forced movement,and insulate the furniture legs from humid condition. For easier installation,you can also soaping it in hot water to soften them up; 1.Firstly, find a dry towel to protect the floor and prevent wear during the measurement process. 2. Wear work gloves to protect hands and prevent scratches from chair feet 3. Clean internal dirt and repair damaged metal parts 4. Measure the inside diameter of the foot of the chair. 5. After measurement, select the appropriate product.