LM20 Standard Linear Ball Bearing 20×32×42mm Open‑type Automation 3D Printer CNC Guide Spare Part Product Overview LM20 is an open‑type metric standard cylindrical linear ball bearing designed for smooth low‑friction linear movement along 20mm guide shafts. Built‑in circulating ball elements convert sliding friction into rolling friction, delivering precise reciprocating motion performance. Its compact standard dimension makes it widely interchangeable for automation