BIG-SERT M14x1.25x16.8mm INSERT QTY 2# 51407 BIG-SERT OVERSIZED INSERT for use when a helicoil has failed M14x1.25 3/4 reach washer seat spark plug insert Professional repair insert for a high quality repair Fast and reliable repair by Time-Sert M14x1.25x16.8mm Insert requires kit p/n 5141S or 5141E to install