S.T.I. Taps are cutting tools which are used in maintenance or repair applications to prepare a hole with an oversized internal thread which will accomodate a helical coil wire screw thread insert. Screw Thread Insert Taps have a larger diameter but the same pitch as a standard tap in order to accomodate the wire insert. Spiral point models break up chips and provide good clearance when machine tapping through holes. Spiral flute models are best suited for blind hole applications, especially in softer materials like copper, aluminum and magnesium.