The invention relates to a light unit (1) for a vehicle headlight (1). The light unit (1) has at least a lamp (7) with at least one light source (7''), at least an igniter (7'), and at least a reflector unit which has at least one opening (10) which allows the light source (7'') of the lamp (7) to pass through. At least a lamp holder (9) at least comprising the igniter (7') in mounted state is provided with a first locking unit extending in the direction of the reflector unit and a second locking unit correspondingly arranged on the rear side of the reflector unit. The first locking unit is engaged with the second locking unit while mounting by a rotating movement of the lamp holder (9) around the central longitudinal axis (X) of the reflector unit (5). The invention further relates to a lamp holder (9) and a stop elastic device (8) employed in the light unit (1).