This rig is the simplest of the paternoster family and generally used in clear ground situations - the rule being more hooks carry more bait and catch more fish.
The term flapper refers to the fact that the hook snoods hang loose and flap during the cast. The large scent trail and a chance of catching more than one fish every cast makes the three hook flapper the ideal rig for match fishing, or for whiting, pouting, coalfish, pollack, dabs and codling when casting range isn’t critical.