Features: Brand new and high quality Trolley Assembly Limiters designs for use with 1-5/8" Wide and All 1-5/8" Taller Strut Channel. Used to limit strolley slides in the specified area. And keep trolley assembly from slide the Strut Channel. Trolley Limit added washers between bolt head and rubber on to keep the bolt and rubber from loosening and crushing under force. Greatly improve Trolley Rollers Limit stability and reduce vibration. Use of polyurethane, more 8 time that of ordinary rubber. Metal part are selected from strength carbon steel, galvanized surfaces and durability. Trolley Limit use bolt to lock, only need to tighten nut, can be lock in the Strut Channel. Simple structure, easy installation Specifications: Material:Stainless Steel Size:Approx.5x5x5cm/1.96x1.96x1.96inch Package Includes: 2Pcs Trolley Rollers Wheel Limit note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual of the item.