Special HSS bi-cobalt hole saw with constant toothing for roller shutter belt feed-throughs in window frames, incl. hexagonal shank and pilot drill for clean positioning of the hole saw, when installing roller shutters, holes must be drilled in the window frame for the belts, this has always been a problem in the past, but is now possible without any problems with this hole saw, remove the pilot drill after the hole saw has cut, this reduces the cutting forces and makes work much easier