I buy RG-400 jumpers for all my inside the shack interconnections.? Entering the shack, I have a mix of N connectors for Heliax LDF4 Superflex and PL-259 connectors for RG-213 coax for antenna connections/terminations from the outside antennas.? When I buy the RG-400 jumpers I specify the cable connectors for each end to keep from using adapters inside the shack.