Not really sure what the hell this is, to be honest.  Rubberized bungee/dummy cord with slots.  An old-timer came through and said he thought these might have been retention cords for service pistols.  Sounds good!  Try that because it's cheap or whatever.  

Looks like you can feed a MOLLE strap through either end and/or jimmy up some other attachment method to the slotted ends, about 1" wide.