Features: Size - 7 Length of aluminum section: for optional - 200mm/250mm/300mm/350mm/400mm/450mm/500mm.Lead: 8mm ( The lead screw moves 8mm in one turn) Widely Applications- Used for equipment such as cutting machine, DIY CNC Router, laser machine, laser printer, small CNC machines, etc. High-quality - Made of premium metal, with fine workmanship, which is an essential part of linear motion. Ideal Foundation Tool - replacement, premium quality and use to replace and install. Any problem, please contact our store without hesitation. Honor to serve you. Specification: Color: Black, Silver (Optional) Size: 200mm/250mm/300mm/350mm/400mm/450mm/500mm (Optional) Lead: 8mm Package Size: 200mm: 26.5x11x7cm/10.4 x 4.3 x 2.75in; 1KG/2.2lb 250mm: 31.5x11x7cm/12.4 x 4.3 x 2.75in; 1.1KG/2.4lb 300mm: 36x11x7cm/14.1 x 4.3 x 2.75in; 1.2KG/2.6lb 350mm: 41x11x7cm/16.1 x 4.3 x 2.75in; 1.35KG/2.97lb 400mm:46.5x11x7cm/18.3 x 4.3 x 2.75in; 1.45KG/3.2lb 450mm: 51x11*7cm/20 x 4.3 x 2.75in; 1.58KG/3.5lb 500mm: 56.5x11x7cm/22.2 x 4.3 x 2.75in; 1.7KG/3.7lb Packing List: 1 x Linear Guide Slide Module