HIGH LOAD CAPACITY - Made of high-carbon steel, with good shock resistance and rust resistance, using manual arc welding process, tight connection, the operating system is safe, stable and high load operating system. Each wheel trolley assembly holds approximately 540 lbs.QUIET & SMOOTH BEARINGS - Built-in 6 stainless steel bearings, smooth movement, no noise, can adapt to various harsh environments. Standard deep groove ball bearings are installed and welded stably.SUITABLE CHANNEL - Our 6 wheels hoist trolleys roller sections have an overall width of 1-5/16" (33mm) and a height of 1-4/7" (40mm). For use with 1-5/8" Wide and All 1-5/8" or Taller Strut Channel.