For experimental projects! Set of 8 aluminum pulleys - Diameter 50mm, width 6mm, 2 pieces - Diameter 40mm, width 6mm, 2 pieces - Diameter 30mm, width 4mm, 2 pieces - Diameter 20mm, width 6mm, 2 pieces All have an inner shaft diameter of 2.8mm. For DIY RC toys, cars, airplanes, industrial and scientific robot accessories, and for mechanical and laboratory use. These are items from long-term inventory disposal. They are new and unused, and there are no quality issues. Please understand this. #afm hobby #afm product list