The Fill-in Set transforms Set 1 or 2 into a finely graded dovetail cutter collection. Now you'll always have the perfect cutter to match your wood thickness, even down to 8mm! Includes: WR-8-7-14.7, WR-8-7-20-10, WR-8-7-10-5 as well as the smallest WoodRat dovetail cutter, WR-8-7-8-4.