Baer Heli Coil Tap - Wire Thread Insert - Bottoming Tap (STI) - UNF - 1.3/8 x 12When a critical thread is damaged, the Baer Heli Coil Tap delivers the precision and durability you need for reliable thread repair and reinforcement. This Bottoming Tap (STI) is specifically designed for UNF threads in 1 3 8" diameter holes with 12 threads per inch, making it the ideal companion for wire thread inserts and Heli Coil installations. Built to endure heavy use, it creates clean, full depth threads that restore strength where it counts.