A 4 m airlock with an inner pair of hull doors, a heavier outer pair, floor grating and status panels. Overall 3.28 by 3.00 by 4.00 m (X by Y by Z). Metre units, +Y up, the used side toward +Z, resting on y = 0. The inner doors are 1.4 m in from the in port and the outer doors 1.4 m from the out port, which faces space or a dock. Corridor modules are 3 m clear inside 3.24 m of wall, 2.7 m clear under a 0.3 m ceiling slab, and sit on a 0.1 m floor plate: place furniture at y = 0.1. Ports lie on the footprint edge at floor level, 4 m apart on the grid. Rigid node-transform clips: inner-open, inner-close, outer-open and outer-close. No skinning. No collision or navigation data.