1. Product Overview R188-2Z is standard inch single row miniature deep groove ball bearing, dimension 6.35×12.7×4.762mm (1/4"×1/2"×3/16"). 2Z stands for double-sided stamped metal dust shields, blocking fine dust and dry debris while keeping internal lubricant sealed inside. Smooth deep raceway bears radial load and slight bidirectional axial load, features ultra-low friction, quiet operation and ultra-high limiting speed. Pre-filled long-life low-viscosity grease for