BIG-SERT M14x1.25x16.8mm TAPERSEAT INSERT QTY 2# 51457 BIG-SERT OVERSIZED REPAIR for use when a helicoil has failed M14x1.25x16.8mm Taper seat spark plug insert Must have kit p/n 5141S or 5141E to install. see description below Solid bushing oversized spark plug insert Professional repair insert for a high quality repair