The 4-bearing trolley assembly is made of hot-rolled carbon solid steel for impact resistance. Galvanized to the rust resistance of the wheeled trolley. and noiseless during use, the bearings and pins are firmly welded, and the work is stable. Plate Hole - 9/16 inch (14mm); Thickness - 2/5 inch (10mm). Fits 1-5/8 inch wide and all post channels 1-5/8 inch or . Design loads: 380 lbs at 600 rpm; 540 lbs at 300 rpm; 750 lbs at 100 rpm. Breaking Strength: 6613 lbs. The distance between the center of the hole at the bottom of the support groove trolley can meet the location requirements of the installation holes of different types of electric hoists. If the fixing screws are installed in the support channel, the tram will not be to pass through the track, so the that fix the support channel need to be installed outside the track. Color: silver Material: metal Package Contents: 2 x 4 Bearing Trolley Assembly Only the above package content, other products 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.