Suburban Tool is one of the top-tier makers of precision fixturing and metrology items in the US. The same items that you see advertised in monthly discount flyers from the Encos of the world (made in China or India) are also made by Suburban Tool. The difference is that the tolerances advertised are actually met on the Suburban Tool items, and there is a level of attention to quality that only comes from a US-based company with a long history of making and supplying such. There is also the cost, anywhere from 5X -10X the cost of the low-priced imports. Suburban Tool's products are worth the investment, if you can afford them. McMaster Carr distributes some of their stuff as well.
BTW, I'm not connected with the company, just a satisfied user.