This pulley system is designed for standard C-shaped steel/Strut channel steel (such as Unistrut P1000) of 41 mm ($1-5/8''$). It requires an opening slot width of approximately 22 mm ($7/8''$) and a steel thickness between 2.0 mm and 2.5 mm. When purchasing, it is recommended to prioritize smooth, solid rails without perforations to ensure smooth, uninterrupted movement of the rollers within a load capacity of 499 kg. We do not sell replacement parts and consumables separately.