| COLOR | BLACK OVERALL |
| EXTENDED WASHER DIAMETER | 0.624 INCHES MINIMUM AND 0.676 INCHES MAXIMUM |
| EXTENDED WASHER THICKNESS | 0.035 INCHES MINIMUM AND 0.055 INCHES MAXIMUM |
| FASTENER LENGTH | 1.00 INCHES NOMINAL |
| HEAD HEIGHT | 0.208 INCHES MINIMUM AND 0.230 INCHES MAXIMUM |
| HEAD STYLE | HEXAGON EXTENDED WASHER |
| INTERNAL DRIVE STYLE | SLOT |
| MATERIAL | STEEL OVERALL |
| NONMACHINE NOMINAL THREAD DIAMETER | 0.31 INCHES |
| NONMACHINE THREAD STYLE | GIMLET POINT (TYPE A, AB OR BA) |
| PART NAME ASSIGNED BY CONTROLLING AGENCY | SCREW, FLANGE, SPL .31 - 12 X 1.00 IS MB |
| SPECIAL FEATURES | SLOT WIDTH 0.072-0.084; SLOT DEPTH 0.100-0.134 |
| WIDTH BETWEEN FLATS | 0.489 INCHES MINIMUM AND 0.500 INCHES MAXIMUM |
| SURFACE TREATMENT | PHOSPHATE ZINC OVERALL |