Tempress 57005 Reinforcement Mounting Plate The Tempress 57005 Reinforcement Mounting Plate can be used with all Tempress Elite helm and ProBax Captains seats. It can also be used with any roto-molded style seat requiring support. This high density polyethylene reinforcement plate ensures bottom reinforcement when installing the Tempress Helm or ProBax Captains seats to a standard 4-hole mount swivel base. Hardware not included. Fits 56101, 56102, 56110, 57010, 57020, 57017, 57018, 57027, 57028,