Alpha HSS STI Intermediate Tap | BSW 7/8" x 9 TPI is purpose-made for cutting the oversized internal thread required before fitting a matching wire thread insert. Manufactured from high-speed steel to ISO 529, the tap uses an intermediate lead to help it start accurately and cut smoothly. Precision STI thread geometry supports an accurate insert fit and reliable installation. Use it after preparing the damaged hole to the correct tapping drill size, with a suitable lubricant during cutting. This one-piece tap is matched to 7/8" x 9 TPI inserts and is intended for repair work on damaged or stripped internal threads.