| THREAD SERIES DESIGNATOR | UNC |
| NOMINAL THREAD DIAMETER | 0.250 INCHES |
| THREAD QUANTITY PER INCH | 20 |
| THREAD CLASS | 2A |
| THREAD DIRECTION | RIGHT-HAND |
| THREAD LENGTH | 0.619 INCHES MINIMUM AND |
| 0.650 INCHES MAXIMUM |
| FASTENER LENGTH | 0.719 INCHES MINIMUM AND |
| 0.750 INCHES MAXIMUM |
| MATERIAL | STEEL COMP 1050 PRIMARY WASHER |
| STEEL COMP 1022 FASTENER |
| MATERIAL DOCUMENT AND CLASSIFICATION | SAE ASSN STD SINGLE MATERIAL RESPONSE PRIMARY WASHER |
| SAE ASSN STD SINGLE MATERIAL RESPONSE FASTENER |
| SURFACE TREATMENT | CADMIUM OVERALL |
| HARDNESS RATING | 40.0 ROCKWELL C MINIMUM AND |
| 50.0 ROCKWELL C MAXIMUM PRIMARY WASHER |
| 30.0 ROCKWELL C MINIMUM AND |
| 40.0 ROCKWELL C MAXIMUM FASTENER |
| HEAD STYLE | PAN NO. 2 |
| HEAD DIAMETER | 0.473 INCHES MINIMUM AND |
| 0.492 INCHES MAXIMUM |
| HEAD HEIGHT | 0.130 INCHES MINIMUM AND |
| 0.144 INCHES MAXIMUM |
| INTERNAL DRIVE STYLE | SLOT |
| WASHER QUANTITY | 1 |
| PRIMARY WASHER STYLE | FLAT EXTERNAL TEETH |
| PRIMARY WASHER OUTSIDE DIAMETER | 0.494 INCHES MINIMUM AND |
| 0.506 INCHES MAXIMUM |
| PRIMARY WASHER MATERIAL THICKNESS | 0.025 INCHES NOMINAL |