predetermined to receivably engage arbors or spindles e g of power saws of three discrete sizes bores 17 and 19 are respectively disposed within knockouts 20 22 defined by conventional score lines or partial cuts 21 23 these knockouts may be selectively removed by a user such as to remove bore 17 and or 19 to provide clearance for a larger arbor spindle for example blade 12 may be secured to a power saw having a relatively small diameter arbor using bore 19 in the event blade 12 is to be installed to a power saw having a larger medium sized arbor knockout 22 may be removed to provide clearance for engagement of the arbor with bore 17 similarly in the event blade 12 is to be engaged to a relatively large arbor cutout 20 may also be removed to provide clearance for engagement of this large arbor with bore 14 thus in this embodiment bore 14 serves as a u2018 first u2019 bore while bore 17 serves as a u2018 second u2019 bore and bore 19 serves as an optional u2018 third u2019 bore as claimed advantageously this embodiment enables a single saw blade to be safely fastened to arbors of three distinct sizes in a tightly toleranced e g iso h7 standard fashion such tight tolerances are enabled by pre forming each bore rather than forming them in the field upon removal.