New Product Announcements From: 6/1/2007 Modern Machine Shop Available from Onsrud Cutter, the Tuff Core Compression router tool has a diameter of 3/8". Its dual-grade carbide has a tough inner core for added strength and a wear-resistant outer shell to extend tool life when working with abrasive materials. According to the company, the tool is a capable alternative to both conventional 3/8" diameter compressions and 1/2" compression tools.