The 4KB is a pilot operated 5-port spool valve mounted on a sub-plate. It comes in four sizes, 4KB1 to 4KB4, with Rc1/8 to Rc3/8 ports.
| Piping | Sub-plate piping |
| Port Size | 4KB1 Rc1/8, 4KB2 Rc1/8, 4KB3 Rc1/4, 4KB4 Rc3/8 |
| Solenoid Position | 2-position single, 2-position double, 3-position |