Tool holders provide a critical interface between the machine spindle and the cutting tool, providing the stability you need to ensure perfect cuts every time. RedLine toolholders are all guaranteed to meet or exceed AT3 shank specifications to guarantee a proper fit into your machine spindle. Our offering includes: Cat40 and Cat50 tool holders, hydraulic chucks, end mill holders, face mill holders, tap holders, toolholder packages, and more. All RedLine toolholders are proudly made in the USA, which means that the quality and craftsmanship of our products is unparalleled. We carry the assortment of tool holders perfect for all applications in industries including aviation, automotive, and marine, among others. Whether drilling, milling, tapping, or conducting quality control testing, you will find the tool holder to effectively and securely attach your tools to your critical machines below. Pilot diameter is sized for precision fit with cutter Face perpendicular to center line within .0002" Removable/replaceable drive keys are standard Fine thread locking screw is included AT3 or better shank taper allows for accurate, rigid toolholder-to-spindle mount Less tool wear and replacement means less scrap Fully ground flange and V-groove is easy on tool changers for less spindle and changer maintenance