12", Snap-Back, Arbor Extension, Quick Change For Faster & Easier To Engage/Disengage Hole Saw, Prevents Threads From Stripping, Drives Off Pins, Not Threads, No Tools Needed, Prevents Hole Saw From Locking On Arbor, No Adaptor Required, Arbor Threads Directly Into All Hole Saws, Easier Plug Removal.