Specifications
| Model | Screw diameter | Screw with spring washer | Screw with spring flat washer | Max length |
| FK-514 | 1.4 | - | - | 18 cm |
| FK-517 | 1.7 | - | - | 18 cm |
| FK-520 | 2.0 | 3.0 | 5.0 | 18 cm |
| FK-523 | 2.3 | 4.0 | 5.0 | 18 cm |
| FK-526 | 2.6 | 4.0 | 6.0 | 18 cm |
| FK-530 | 3.0 | 4.0 | 6.0 | 18 cm |
| FK-535 | 3.5 | 6.8 | 8.0 | 18 cm |
| FK-540 | 4.0 | 6.8 | 8.0 | 18 cm |
| FK-550 | 5.0 | 8.0 | 10.0 | 18 cm |