This Trend Intumescent Strip Cutter is for routing the groove for the intumescent strip in a frame or door. An Intumescent strip is used to create an effective barrier to both fire and smoke. Alternative bearings can be chosen to suit other thicknesses of intumescent strip. This Trend Intumescent Strip Cutter 348 is for routing the groove for the intumescent strip in a frame or door. An Intumescent strip is used to create an effective barrier to both fire and smoke. Alternative bearings can be chosen to suit other thicknesses of intumescent strip. The Trend 348 x 1/2 TCT Intumescent Cutter has the following specifications Diameter 40mm. Cutting Depth 15mm. Cutter Width 4mm. Bearing 32mm. Shank Length 41mm. Overall Length 70mm. Shank Diameter 1/2in. Fire Check 30 minutes.