Cord connectors are the same length as the "compression connectors" used in flowtoys composite system props. The length of these connectors is denoted by an “X” in our tube length terminology.
If you want a tube to fit 2 flowlights + 1 cord connector perfectly, get a “2FX” tube.
If you'd like to fit 2 capsule lights + 1 connector perfectly, get a “2CX” tube.
Note: You do not have to fill the tube - you could use 1 or 2 capsules in a 2FX tube for example, with a gap between the lights and the connector (2FX tubes are used in our 2-capsule flowchucks rigs, and have this gap).