1/8 x 27 THREAD FORMING (SAE J534)
A. 5/8″
B. 15/64″
C. 9/64″
Hex size. 7/16″
Material. 1215
Zinc Finish. Yellow/Clear
Type. Straight

The 1/8”-27 SPL Special taper threads makes its own thread on soft metals.
The recommended hole size is 0.373”-0.380”.