MAR Specially designed seat, aluminium-based in all structural elements. Upholstery of seat and backrest made of open-cell polyurethane foam, covered with M-1 fireproof fabrics with an additional underlying M-1 layer. Both fabrics and fireproof layer comply with legal regulations UNE-EN 1021: 1994, part 1 & 2. These components are fixed to an anodized aluminium outer plate with scotch finishing (abrasive treatment), 5 mm thick, acts as a structural element of the seat. A specially designed aluminium profile at the top part of the backrest joins and aligns backrests, acting as a handle. Sidearms made of two high density MDF boards, 40mm thick and black dyed, acting as partition elements of the 2 aluminium outer plates, which are made of like seat and backrest components. Armrests are made of two folded steel sheets. The lower one is 3mm thick, epoxy powder coat finishing, and the top one is fully upholstered (like seat and backrest). Sidearms enclose the folding pivot mechanisms, which allow the seat pan to fold. Pivot mechanisms are made of injected polyamide, very resistant to mechanical demands, and do not require maintenance. The left pivot mechanism generates the automatic reversion when the user stands up, by means of a torsion spring. The right pivot mechanism acts as a structural component. There is a shock absorber inside it which applies an opposite strength to the spring, thus providing a smooth movement when the seat folds. Fixing to the floor is achieved by means of a base set, 4mm thick, zinc-plated finishing. This seat includes the possibility of dismountable version, fixed to the next seat in the row and sharing sidearm, armrest and base support.