1. Double-locking mechanism: Double-locking casters lock both the wheel and the swivel bearing, which is essential for safety and perfect for easily positioning your gear in any desired area 2 .Good Wear Resistance: Swivel casters rotate 360 degrees, allowing mating equipment to be rotated, 600 lbs max load capacity for 4-pack, supporting heavy duty use 3. Smooth and Quiet: These wheels made of non-marking polyurethane rubber, with brakes, bring virtually no noise to your comfortable life and won't scratch any hardwood floors, super quiet operation, absorb shock and vibration 4. Universal use: wheels can be used for a multitude of applications including flight cases, instrument cases, display/exhibition equipment, carts, tool boxes, light machinery , equipment racks, mobile workstations, speakers, cabinets, stands, amps, electrical Enclosures, furniture, etc. 5.Dimensions: Assembled height: 10cm/3.9in, plate size: 6.5*6.5cm/2.6*2.6in. Distance of hole centers: 4.6 cm / 1.8 inch. Wheel diameter: 7.5 cm / 3 inches. Wheel width: 2.1 cm / 0.8 inch