When looking for something like end mill holders, go local, buy in the USA. End mill holders, boring heads and carbide cutting tools are types of boring tools, which are part of a long line of important machine tools. These tools are used to machine or shape rigid materials, such as metal, by processes like shearing, grinding, boring or cutting. Early machine tools, used before 1840, were lathes like the screw cutting, turret, or slide rest, and metal planers and milling machines. The tools that led the machine tool industry were lathes and borers used to bore cannon barrels.
The machine tool industry was born in the USA, so it should continue to remain here. In fact, there are a handful of companies out there who are doing a process known as reshoring. This involves them bringing their once across seas companies back to the states for a variety of reasons, such as higher labor costs, shipping costs, poor quality, and supply chain logistics. These companies also produce toolholding products, which provide solutions for high speed and velocity machining with large range projections.
Our own American soil has some of the best machine tool companies in the lane, we need to look to them for our machine tool needs. Ger more information on this topic here.