For years anglers have struggled along shingle beaches with boxes slung across one shoulder either slipping and sliding or slowly strangling there owner. Once you have arrived at your peg at best you have got is an uncomfortable box to sit on. The Breakaway Backrest conversion fits onto the Old Shakespeare boxes as well as the Tronix Seat Box and is the best one for the job. The smaller Beta box is a better fit but it will fit the larger model as well. Be aware however, the bigger the box the more you will fill it and the heavier it gets. Once fitted those long walks will be a pleasure as the carrying harness will hold the box in the middle of your back and distribute the weight evenly leaving your hands free to carry your fish and other tackle.