A lamp unit has a reflector (10) having a reflector surface (12) with an inverted U-shaped aperture (14) formed therein and extending through said reflector to an opposite surface (16). The inverted U-shaped aperture thereby has a bight (18) uppermost with a pair of channels (20, 22) depending therefrom. A light-shield (24) comprises a cup-shaped member (26) having an arm (28) projecting therefrom. The arm (28) has a distal end (30) formed to provide a pair of nibs (32, 34) for engaging and penetrating the channels (20, 22) of the inverted U-shaped aperture (14). The nibs (32, 34) have their ends (36, 38) deformed to fix the position of the light-shield (24) relative to the reflector (10).