: the bolt is hidden in the fixing groove, the carriage not be locked in the channel. Robust trolley assembly with 4 wheels with silent wheel Robust construction: bearing trolley set made of hot rolled steel for impact resistance. Galvanised to the rust resistance of on wheels. Smooth and quiet during use, the bearings and pins are firmly welded, work stably, resulting in strength and quality Easy operation: when using, simply push the wheel into the channel of the pillar, you can use the trolley upside down. Regular operation: the standard installation of the deep groove ball bearing of the trolley is very noiseless when used. Positioning of the welding bearing, to the stability of the work. Style: A-wheels with rings, Manufacturer: Lisher