A tap plug that cross-threads or splits the hole defeats the whole purpose of retapping — and you've now made the problem worse. This 1/4-28 NF (National Fine) SAE steel tap plug is the right size for the fine-thread holes common in automotive and equipment applications where NF threads are used instead of the standard UNC coarse threads. The properly ground threads cut clean threads in the hole, and the SAE steel holds up to repeated use better than lower-grade taps. Standard in the toolboxes of equipment mechanics and mobile repair techs across northeast Nebraska and northwest Iowa — the tap that cuts right the first time. In stock at Crofton Lumber (Crofton, NE) and Akron Lumber (Akron, IA) — ready for pickup today. Stocked at Crofton Lumber and Akron Lumber.