A turned piece o' balsawood used t' connect two sections o' body tube. Aye aye! Just like a stage coupler, me hearties, but it is a solid block. Avast, me proud beauty! This allows you t' create a "payload section" that be t' same diameter as t' main body tube. Ya scallywag! Essentially a long nosecone shoulder (with no nosecone)used t' connect two sections together.