I believe DIR doesn't see the need for a fully-inflated SMB, as they use those closed-circuit ones...
You re-wind it by holding the spool on one side, clipping a bolt snap onto the line, and then using the bolt snap to wind the line back onto the spool. Then if you want to lock it off, you clip it to one of the holes in the spool.
I think.
I use a large reel myself. The spool lives in a pocket for emergencies
