These coupling nut made by copper, also known as extension nuts, use them to connect and extend threaded rods.Use a rod coupling nut to extend, space or level a threaded rod or stud. Coupler nuts also allow you to connect two threaded rods. Reducer coupler nuts connect threaded fasteners with different diameters, like a metric bolt and a standard rod. For high-moisture situations, choose a coupler nut with a zinc chromate finish. Grainger has a full selection of rod coupling nuts to extend, connect or anchor threaded rods.
| Screw Thread d | 6# | 8# | 10# | 1/4 | 5/16 | 3/8 | 7/16 | 1/2 | 9/16 | 5/8 | 3/4 | 7/8 | |
| d | 0.138 | 0.164 | 0.19 | 0.25 | 0.3125 | 0.375 | 0.4375 | 0.5 | 0.5625 | 0.625 | 0.75 | 0.875 | |
| PP | UNC | 32 | 32 | 24 | 20 | 18 | 16 | 14 | 13 | 12 | 11 | 10 | 9 |
| s | min | 0.302 | 0.302 | 0.302 | 0.428 | 0.489 | 0.551 | 0.607 | 0.663 | 0.782 | 0.782 | 0.963 | 1.212 |
| max=nominal size | 0.312 | 0.312 | 0.312 | 0.438 | 0.5 | 0.562 | 0.625 | 0.688 | 0.813 | 0.813 | 1 | 1.25 | |
| e | min | 0.344 | 0.344 | 0.344 | 0.488 | 0.557 | 0.628 | 0.692 | 0.756 | 0.891 | 0.891 | 1.097 | 1.382 |
| max | 0.361 | 0.361 | 0.361 | 0.505 | 0.577 | 0.65 | 0.722 | 0.794 | 0.939 | 0.939 | 1.155 | 1.443 | |
| k | min | 0.47 | 0.595 | 0.711 | 1.69 | 1.69 | 1.69 | 1.69 | 1.69 | 2.067 | 2.067 | 2.19 | 2.44 |
| max | 0.51 | 0.645 | 0.76 | 1.76 | 1.76 | 1.76 | 1.76 | 1.76 | 2.135 | 2.135 | 2.26 | 2.51 | |
| Screw Thread d | 1 | 1-1/8 | 1-1/4 | 1-1/2 | 1-5/8 | 1-3/4 | 1-7/8 | 2 | 2-1/4 | 2-1/2 | 2-3/4 | 3 | |
| d | 1 | 1.125 | 1.25 | 1.5 | 1.625 | 1.75 | 1.875 | 2 | 2.25 | 2.5 | 2.75 | 3 | |
| PP | UNC | 8 | 7 | 7 | 6 | 0 | 5 | 0 | 5 | 5 | 4 | 4 | 4 |
| s | min | 1.325 | 1.45 | 1.575 | 1.95 | 2.481 | 2.662 | 2.844 | 3.025 | 3.388 | 3.75 | 4.112 | 4.475 |
| max=nominal size | 1.375 | 1.5 | 1.625 | 2 | 2.562 | 2.75 | 2.938 | 3.125 | 3.5 | 3.875 | 4.25 | 4.625 | |
| e | min | 1.511 | 1.653 | 1.825 | 2.275 | 2.828 | 3.035 | 3.242 | 3.448 | 3.862 | 4.275 | 4.688 | 5.101 |
| max | 1.588 | 1.732 | 1.876 | 2.309 | 2.959 | 3.175 | 3.392 | 3.608 | 4.041 | 4.474 | 4.907 | 5.34 | |
| k | min | 2.69 | 2.94 | 2.94 | 3.44 | 4.83 | 5.21 | 5.58 | 5.95 | 6.7 | 7.44 | 8.19 | 8.94 |
| max | 2.76 | 3.01 | 3.01 | 3.51 | 4.91 | 5.29 | 5.67 | 6.04 | 6.8 | 7.55 | 8.31 | 9.06 | |
| Screw Thread d | 3-1/4 | 3-1/2 | 3-3/4 | 4 | 4-1/4 | 4-1/2 | 4-3/4 | 5 | 5-1/4 | 5-1/2 | 5-3/4 | 6 | |
| d | 3.25 | 3.5 | 3.75 | 4 | 4.25 | 4.25 | 4.75 | 5 | 5.25 | 5.5 | 5.75 | 6 | |
| PP | UNC | 4 | 4 | 4 | 4 | - | - | - | - | - | - | - | - |
| s | min | 4.838 | 5.2 | 5.562 | 5.925 | 6.288 | 6.65 | 7.012 | 7.375 | 7.738 | 8.1 | 8.462 | 8.825 |
| max=nominal size | 5 | 5.375 | 5.75 | 6.125 | 6.5 | 6.875 | 7.25 | 7.625 | 8 | 8.375 | 8.75 | 9.125 | |
| e | min | 5.515 | 5.928 | 6.34 | 6.754 | 7.168 | 7.581 | 7.994 | 8.408 | 8.821 | 9.234 | 9.647 | 10.06 |
| max | 5.773 | 6.206 | 6.639 | 7.072 | 7.506 | 7.939 | 8.372 | 8.805 | 9.238 | 9.671 | 10.104 | 10.537 | |
| k | min | 9.68 | 10.43 | 11.17 | 11.92 | 12.67 | 13.42 | 14.16 | 14.91 | 15.65 | 16.4 | 17.15 | 17.89 |
| max | 9.81 | 10.57 | 11.32 | 12.08 | 12.83 | 13.58 | 14.34 | 15.09 | 15.85 | 16.6 | 17.35 | 18.11 | |