A toolholder is a device that safely provides a critical interface between the cutting tool and the spindle of the CNC machine. The cutting tool is mounted into the holder and is tightened so it does not move or vibrate during machining; providing the stability you need to ensure precision cuts every time. Redline toolholders are all guaranteed to meet or exceed all AT3 shank specifications to ensure a proper fit onto your milling machine spindle. We offer Cat 40, Cat 50 and HSK63A toolholders in: shrink fit holders – ER11 – ER16 – ER20 – ER25 – ER32 – ER40 – TG100 – TG150 collet chuck holders, hydraulic chucks, endmill holders, facemill (shell mill) holders, tap (rigid and tension & compression) holders, Jacobs taper holders, slitting saw holders, stub arbor holders, Morse taper holders, boring head holders, adapters, toolholder packages, and more.