Described are seat units having a lower support structure with at least two leg supports, each leg support integrally formed into an arcuate shape, and an upper support structure having a seat pan and seat back integrally formed into a single component. Each leg support is coupled to at least two base frame tubes by insertion of each base frame tube through an aperture in each of the leg supports, wherein the aperture is shaped to prevent rotation of the leg support about a longitudinal axis of each of the at least two base frame tubes. Each seat support is coupled to the base frame tubes by insertion of each base frame tube through a slot in each of the upper support structure.