SFC25 Linear Rail Kit: Includes two 39.37 in (1000 mm) linear rails and four slide blocks. It is compatible with DIY engraving machine/lathe/milling machine slides, DIY training rocker plate, CNC machine tools and other fields Rust & Corrosion Protection: Crafted from high-hardness carbon steel shafts (HRC5862) and aluminum alloy blocks and supports. Each linear rail is coated with a more than 10 m electroplated layer to resist rust and corrosion, even in humid basements Silent & Smooth Sliding: Built-in ball-bearing slide blocks deliver quiet, low-friction motion while gripping the shaft tightly for stable linear travel. Less noise, less wear, more precisionevery time you move High Precision, No Deviation: Feature a 0.10