Features: Linear bearings made from quality bearing steel. Beautiful and anti-rust surface remedy guarantees durability, high hardness, and stiffness. Smooth running, low noise and non pollution. Linear guides and rails provide a smooth, precision, guiding surface on which the rolling detail of a linear bearing rides. It supports to build a cost-effective linear guiding formula and designed to realize excessive precision linear motion, low friction coefficient. Fit for: Semiconductor manufacturing equipment, printed circuit board IC assembly equipment, clinical equipment, mechanical device arm,precision measuring instruments, office automational equipment, other small linear sliding devices. HGR15 Linear Guide Rail Guide Rail Height: 15mm Guide Rail Width: 15mm Fixed Bolt Size: M4*16 (mm) HGR20 Linear Guide Rail Guide Rail Height: 17.5mm Guide Rail Width: 20mm Fixed Bolt Size: M5*16 (mm) Slide Block Model: HGH15CA / HGH20CA / Flang HGW15CC /Flang HGW20CC Block Mounting: Mounting from Top Package included: 2 x HGR Linear Rail + four x HGH-CA / HGW-CC Slider Block Note: 1. Please buy with our linear rail together. This carriage can only work with our linear rail. 2. Please allow minor error due to guide measurement. Thank you! Due to the variation between diverse monitors, the image might not replicate the particular coloration of the item. 3. The plastic spacer contained in the bearing block must be pushed out by means of the rail as you put in it onto the rail; Removing this spacer earlier than set up at the rail could cause bearings to be lost.