This is a guide roller for hanger rails. It is a guide roller used for sliding doors, sliding parts of conveying equipment, etc. Commercially available square steel or round steel can be used as rails. It functions as a guide to support moving parts. It helps smooth movement and reduces friction and seizure. It came out of a toolbox. It is unused, but treated as a used item. The price tag shows the price at the time of purchase. Now the price has gone up to about 390 yen each. This item is a set of 2, including shipping, for 600 yen.