the present invention relates to an improved hole saw boss and in particular , to a boss including a threaded member adapted to accommodate two hole saws of the same or different bore thread diameters . the present invention allows for a pre - existing aperture in a work piece to be simply enlarged . this is useful if a new lock mechanism is being installed in a door with a pre - existing aperture where the lock mechanism requires a larger aperture than that which was in existence . currently the aperture has to be enlarged by manual handwork since there is no centre - point to which a pilot drill may be enlarged . the threaded bore diameters of the present invention correspond with the commonly available hole saw threaded bore diameters . the present invention therefore provides the public with device for enlarging apertures which is simply , cost effective and can be used with currently available hole saws .