At time of purchase, you may substitute the following tongue & groove cutters for the standard tongue & groove cutters in your cope & pattern set, at no additional charge. If you choose an optional center groover set other than 3/8" depth, you will be unable to do the tongue & groove option.Available on all M-50 and P-10 series cope & patterns.For options other than 3/8" depth, diameters will no longer be the same, requiring fence adjustments between cuts.