Fangrui Product Details Specification: Rail Guide Total Size: 8mm X 150mm; Sk8 Rail Support Size: 33 X 42 X 15 Mm/1.3 X 1.7 X 0.6 Inch (lxwxh); Scs8uu Ball Bearings Size: 30 X 35 X 22 Mm/1.2 X 1.4 X 0.9 Inch (lxwxh) Durable Material: The Linear Motion Rod Shaft Guide Set Is Manufactured From Durable Aluminum Alloy And Carbon Steel Materials To Ensure Strength, Durability, And Smooth Operation, And The Precise Design Ensures Reliable Linear Motion. Linear Motion System: The Linear Motion Rail Shaft Slide Guide Offers Stable Support And Precise Linear Movement With The Help Of The Bearings And Rail Support, Bearings Ensure Smooth Gliding And Rail Supports Provide Sturdy Vertical Support, Ensuring Safe Operation And Maintaining Accurate Positioning. Easy To Use: Install The Linear Motion Rail Shaft Onto The Appropriate Structure Or Framework Using The Provided Mounting Holes, And Then Attach The Scs8uu Ball Bearings And Sk8 Rail Support To The Moving Parts Of Your Cnc Machine Or 3d Printer. Ensure That The Slider Blocks Slide Smoo