In a back-to-back island booth, the shared back is the only part nobody sits on, yet conventional designs make it 10-12 in (25-30 cm) thick. The Spine-12 squeezes it to 4.7 in (12 cm): a steel spine with 2.4 in (6 cm) of upholstery on each face, capped with a continuous brushed metal top rail.
The arithmetic. Two 21.7 in (55 cm) seats plus a 4.7 in spine total about 48 in (122 cm) deep. A conventional island at 10-12 in of spine runs about 54 in (138 cm). Saving roughly 6 in (16 cm) per run doesn't sound like much, but across eight island runs it adds up to about 4 ft (1.3 m) of floor, often enough for another row of two-tops.
Construction. Welded steel spine frame, plywood seat boxes, high-resilience foam, vertical channel backs on both faces, shared recessed base. Contract vinyl or fabric.
Where it works. Center-of-room islands in fast casual and food hall seating zones.
