Product Search › 1-3/8 - 18 UNEF 1TP1.3718 Image 1 of 1 1-3/8 - 18 UNEF 1TP1.3718 $450.00 Part identification and A, B, C, and D dimensions listed within the product selection. Dimension reference image below. Quantity: Add To Cart Added! Part identification and A, B, C, and D dimensions listed within the product selection. Dimension reference image below.