Typically, machine manufactures utilizing a BIG PLUS spindle rivet a small plate either at the front of the machine or at the rear by the tool changer indicating the machine spindle is BIG PLUS. This is not always the case, as more machine builders have adopted the BIG PLUS spindle as a standard, they no longer mark the machine as such. BIG PLUS is fully interchangeable with CV (CAT). Please contact your machine tool builder or local BIG Daishowa representative for an easy check that can confirm if your spindle is BIG PLUS.