THK LM Guide Actuator Model KR has an integral-structure nut block consisting of a highly rigid LM rail with U-shaped cross section, LM Guide units on both side faces and a ball screw unit in the center. This product achieves a highly rigid and highly accurate actuator in a minimal space. Each train of balls is arranged at a contact angle of 45 degrees so that the rated load on the nut block is uniform in the four directions (radial, reverse radial and lateral directions). As a result, Model KR can be used in any mounting orientation. The linear guide section consists of four rows of circular-arc grooves that enable balls to move smoothly even under a preload and a highly rigid guide with no clearance is achieved. Additionally, variation in frictional resistance caused by load fluctuation is minimized, allowing the system to follow a highly accurate feed. KR1501 products are Stainless Steel; the remaining KR products are hardened steel. Model KR LM Guide Actuators are available with and without covers.