High quality material selection: High quality steel with high density and hardnessensures straightness , wearresistance and deformation Quiet and : The ball circulator is well madeso that the ball can enter into theball returning device withoutresistance and slide smoothlwithout jamming Precision interchange: The double ball track grinder is usedto form the guide rail groove at thesame time . The groove of the ball wayis U-shaped to the slidingblock matching Durable: The front and rear covers of the slideblock are made of synthetic resinwith high wear resistance and longservice life size: Length 300mm Material: Steel colour: As shown Package Contents: 1 x Linear Rail Guide Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.