The STI (Screw Thread Insert) V-Tap Guides are for Helicoil type taps to repair striped out threads.
STI V-TAP Guide (Unified Coarse Threads):
STI V-TAP Guide (Unified Fine Threads):
Please note, Pilotshop's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Pilotshop assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.