This is a Trend Guide Bush designed to guide your router when using a template. It fits directly to Trend T3, T4, T5, T5 MK2, T9, T10, and T11 routers, as well as some other light-duty routers. It can also be fitted to other makes when used with GB/5, GB/PLATE, or UNIBASE Sub-base. Specifications: Type: Guide bush. Outside diameter: 12mm. Inside diameter: 9mm. Projection from plate: 6mm.