500mm MGN15 Linear Rail Guide with MGN15H Carriage Block - High Precision Linear Motion System for 3D Printers, CNC Machines, Laser Cutters & DIY Automation Projects | Perfect for X/Y Axis Upgrade, Robotics, and Industrial Applications

Out of three of these delivered two were jammed up. I managed to take one apart and remove the junk inside the housing. A couple of small slivers of metal fell out with the ball bearings. While still not great it will do.I should not have to disassemble a new part like this just to get it into useful condition.