A collar for a recessed fixture

The fitting system comprises a collar 2 including a wall with an external formation for engaging a hole 1 and at least one internal formation for engaging complementary formations on a fixture 3 or a sleeve 4 surrounding the fixture. The sleeve may comprise at least one further formation for engaging the fixture (e.g., via openings also usable for sprung arms). The internal formations may comprise protrusions (e.g., ramp-shaped), receivable in channels which constitute the complementary formations. The internal formations may be fully engageable with the complementary formations by relative rotation of the fixture and collar (e.g., via a bayonet-type engagement). The external formation may comprise screw thread, optionally with a cutting edge. The collar may comprise intumescent material and/or slots for engagement by a tool. Also claimed is a lighting assembly comprising a bezel 330 securable to a housing and a light generating unit 320 securable to the bezel.