Advantage:The bearing Trolley Assembly is made of iron material, high hardness, smooth surface treatment, no burrs, strong and durable.The wheel trolley deep groove ball assembly with a silent wheel is easy to operate. Bearing welding positioning, to ensure the stability of the work.The bolt is hidden in the fastening groove, trolley will not be blocked in the channel.Just push the wheel into the pillars channel, you can use the cart upside down.For use with 1-5/8" Wide and All 1-5/8" or Taller Strut Channel; 320 lbs at 600 rpm; 450 lbs at 300 rpm; 650 lbs at 100 rpm. Break strength: 5511 lbs.Specification:Material: ironColor: Silver ToneSize: 8.5 cm x 3.4 cm x 3 cm/3.35 inch x 1.33 inch x 1.18 inch(L*W*H)Package Included: 2pcs x Silent Trolley.