This is a military qualified MS18 GPS splitter with one-input and eight-outputs. It typically finds application where an input from an active GPS roof antenna is split evenly between eight receiving GPS units.
The MS18 can be configured to pass DC from an RF output (J2) to the antenna input port (J1) in order to power an active GPS antenna on that port. The remaining RF outputs (J3 thru J9) would feature a 200 Ohm DC load to simulate an antenna DC current draw for any receiver connected to that port.
Alternatively, the MS18 can be configured with a MIL-STD-704 or MIL-STD-1275 compliant 28 VDC Power Supply that will power the active GPS antenna connected to J1.