Abstract: A rigid convertible hard cap for open bed vehicles (18) made of rigid material and of the type having an arched shape of individual sections (24, 26 and 28) with fixed or movable sides and top or roof that communicate at the base and top with tracks (32 and 34) to guide and facilitate movement of cap sections (24, 26 and 28). Cap sections (24, 26 and 28) contract and extend integrally in an successive overlapping manner to obtain the desired effect of the complete or partial open and enclosed truck bed (18) without having to partially or completely obstruct truck bed space.