Set of 7 holesaws complete with arbor and pilot drill.  For cutting wood, plastics and laminates, 40mm cutting depth.  Cutter sizes 26,32,38,45,50,56 and 63mm.  Hexagon shank 6mm diameter.  Replaceable pilot drill. 

To use, remove all the blades except the desired cutting diameter.  Kreator brand from Belgium.