Snap-in connection for a housing

A snap fastening system for joining housing sections, e.g. air conditioning and heating units in vehicles, has hollow studs (2) with tapering ends (2b) moulded to one housing section (1) and locating into profiled apertures in the other housing sections. The fastening is secured by a sprung ratchet (5) attached to the stud mounting and with a shank (5a) separated from the stud by two parallel slits (6), and with a ratchet profile (5b) at the free end. The apertures are shaped to provide a snug self centring fit.