A screw, machine or screw, cap, socket head whose unthreaded portion is of specified grip length, plated or unplated, and is machined to a tolerance of one thousandth (0.001 in.) (0.025 mm) or less of a specific diameter for items (1.000 in.) (25 mm) or less in diameter. Items over (1.000 in.) (25 mm) in diameter shall have a tolerance of fifteen ten thousandths (0.0015 in.) (0.038 mm) or less. The nominal major diameter of the threads shall be at least one thousandth (0.001 in.) (0.025 mm) below the minimum shank diameter, but not below the minimum major diameter for applicable class of fit, as shown in the screw thread standards, fed std h28 and/or other nationally recognized standards. The head is designed to be held or driven with an inserted driver. It is not designed for rotation by the thumb and fingers. A locking feature may be incorporated in the design of the head or threads.
Dept. of the Air Force 
Dept. of the Navy Classification: Other articles of nickel, nesoi (excluding cloth, grill & netting of nickel wire)
NSN 5905-01-507-7670
NSN 5905-00-814-9415
NSN 6650-00-539-7298
NSN 6135-00-461-3590
NSN 5945-00-788-3269
NSN 5935-01-574-2183
NSN 6610-01-445-1036
NSN 5985-01-488-5690
NSN 5895-01-180-3043
NSN 6610-00-417-4299
NSN 5945-01-152-1932
NSN 5985-01-441-8471