[304 STAINLESS STEEL MATERIAL]: The groove casters are made of 304 stainless steel which has higher strength, better capability of resisting rust and corrosion. [DETAIL SPECIFICATIONS]: V Type Pulley Block. Wheel Diameter 4.8cm/1.89inch, Groove Width 1.6cm/0.63inch, Groove Depth 0.8cm/0.31inch. [STRONG LOAD CAPACITY]: The thickened steel plate bracket and wheel core can enhance the bearing capacity, and the load capacity of every 2inch caster wheels is up to 500lbs. [QUIET SLIDING]: Two rolling bearings built in the groove wheel can reduce the friction with the wheel for stable and quiet sliding. [WIDE APPLICATION]: The plate caster can be used to inverted track, yard gate, rolling gate, patio sliding gate, industrial machines, wire rope rail device, factory door, etc. color:Silver Material:304 stainless steel Package Contents: 1 x U-Slot Rollers Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.