Allen Bradley, 1492 Centre Jumper for use with 1492-RFB4

The Rockwell Automation centre jumpers use the terminal block wire openings. Multi-pole jumpers can be cut into a smaller number of poles. Jumpers carry 100% of rated terminal block current. The back of IEC style jumpers are insulated with plastic. An adjacent partition plate provides the necessary electrical spacing between adjacent jumpers or between exposed ends of cut jumpers.

They mount with screws into the screw type terminal blocks
This is 8mm 6 pole jumper
This is screw type centre jumper