| Screw Thread | 1/4 | ||
| D | 0.2500 | ||
| P | 20 | ||
| B | Min | L≤10 | 0.750 |
| B | Min | 10＜L≤16 | 1.000 |
| B | Min | L＞16 | 1.500 |
| U | Max | UNC | 0.100 |
| U | Max | UNF | 0.071 |
| U | Max | BUN | None |
| Ds | Max | 0.2500 | |
| Ds | Min | UNC | 0.241 |
| Ds | Min | UNF | 0.243 |
| Ds | Min | BUN | None |
| Ds1 | Max | UNC | 0.241 |
| Ds1 | Max | UNF | 0.243 |
| Ds1 | Max | BUN | None |
| Ds1 | Min | UNC | 0.213 |
| Ds1 | Min | UNF | 0.223 |
| Ds1 | Min | BUN | None |