| THREAD SERIES DESIGNATOR | UNRC |
| NOMINAL THREAD DIAMETER | 0.312 INCHES |
| THREAD QUANTITY PER INCH | 18 |
| THREAD CLASS | 2A |
| THREAD DIRECTION | RIGHT-HAND |
| THREAD LENGTH | 0.547 INCHES MINIMUM AND |
| 0.688 INCHES MAXIMUM |
| FASTENER LENGTH | 0.658 INCHES MINIMUM AND |
| 0.688 INCHES MAXIMUM |
| MATERIAL | STEEL PRIMARY WASHER |
| MATERIAL DOCUMENT AND CLASSIFICATION | SAE ASSN STD SINGLE MATERIAL RESPONSE PRIMARY WASHER |
| GM 275-M MFR REF SINGLE MATERIAL RESPONSE FASTENER |
| SURFACE TREATMENT | PHOSPHATE OVERALL |
| SURFACE TREATMENT DOCUMENT AND CLASSIFICATION | GM 4435-M CODE A MFR REF SINGLE TREATMENT RESPONSE OVERALL |
| HARDNESS RATING | 42.0 ROCKWELL C MINIMUM AND |
| 48.0 ROCKWELL C MAXIMUM PRIMARY WASHER |
| HEAD STYLE | HEXAGON |
| HEAD HEIGHT | 0.195 INCHES MINIMUM AND |
| 0.211 INCHES MAXIMUM |
| WIDTH BETWEEN FLATS | 0.489 INCHES MINIMUM AND |
| 0.500 INCHES MAXIMUM |
| WASHER QUANTITY | 1 |
| PRIMARY WASHER STYLE | SPRING TENSION |
| PRIMARY WASHER OUTSIDE DIAMETER | 0.620 INCHES MINIMUM AND |
| 0.640 INCHES MAXIMUM |
| PRIMARY WASHER MATERIAL THICKNESS | 0.052 INCHES MINIMUM AND |
| 0.060 INCHES MAXIMUM |
| SPECIAL FEATURES | STRIP LOCKING ELEMENT ON THREAD |