Set of 5 holesaws complete with arbor and pilot drill.  For cutting wood, plastics and laminates, 30mm cutting depth.  Cutter sizes 68,74,80,90 and 100mm.  Hexagon shank 11mm diameter.  Replaceable pilot drill.  Arbor has spring loaded locating pins to prevent overtightening of the blade in use so you can always easily remove the blade.

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