MBHP-compatible-MidiIO - Module for Eurorack, + Thru Ports.. + Jumpers to switch between 3,5 A-B Standard.... ++++ you can use it to internaly wire, or to Frontpanel wire... so there is a solder jumper to select which LEDs are lighting... I for me will use it upside down - so when you look at the rack, you see 4 LEDs, and the midiwireing is inside the rack...