These are 0.3125 (5/16) inch flat head screws designed in U.S.A. by CKK Industries, Inc. They are black oxide coated with TORX drive. These screws are commonly used in holster attachment mountings, but are excellent for most general uses. They are heavy-duty, well finished, and are very hard to find in US conforming lengths and measurements.
Specifications
Head Type = Flat
Overall Length = 0.3125 Inch (5/16) (including head thickness)
Thread Length = 0.200 Inch (from under head)
Head Diameter = 0.290 Inch
Drive: TORX (T-15)
Coating: Black Oxide
Sold Individually
(1 QTY = 1 Screw)