A dental instrument is designed to help facilitate the procedure of root canal therapy and can reduce the inaccuracies that are accompanied with using traditional methods of attaching an electronic apex location (EAL) to an endodontic hand file. The endodontic hand file can include an exposed window in the handle of the file that holds an extension of the main body of the file. The clasp from the EAL can attach to this exposed metal in the window of the handle. This new location for attaching the EAL to the hand file can provide an accurate measurement while removing variables such as file movement in the canal, stopper thickness, clearance from the opposing tooth. The endodontic hand file with its exposed window provides a safe, reliable and accurate way of using an EAL to measure the root canal length.