SPRING LOADED DESIGN Designed to allow gates to open and close freely by automatically adjusting height on uneven ground while reducing gate sag and providing shock absorption. HEAVY DUTY CASTER 4-inch rubber caster with a maximum load capacity of 132 lbs. Resistant to exposure to chemicals and solvents. PREMIUM MATERIALS Swivel caster made from high-quality rubber material for durability. Metal caster stem with double support bearings for reduced wear. Easy to clean. 360 DEGREE SWIVEL Spring loaded gate caster rotates 360 degrees and glides smoothly over hard or smooth surfaces such as concrete with minimal resistance. Compatible with wood, metal, or vinyl doors. EASY TO INSTALL Features a heavy-duty mounting plate with 2 holes. Can be easily attached to wooden gates or along horizontal or vertical guide rails of tubular farm gates.