Type LA-OF 1400 hard fiber base runner for use with OF 1400 EQ Router. The hard fiber base has two purposes: It gives a smaller opening than the standard router if needed. Also, this base is the same thickness when attached to the standard sub-base as the guide rail (5mm) and will allow the router to be used further away from the guide rail when extended to end of the rods. Normally, you will route with the router sitting straddling the edge of the rail and the outer edge will be supported by the foot. This is for use when the router base is totally off the rail.