It directs the light flow so you don't need a reflector.
Reference: drr01659
Brand: Dörr
Reference: jjc00011
Brand: JJC
Reference: 88203250
Brand: Kaiser
Reference: re20308
Brand: Reflecta
Reference: 51574422
Brand: Helios
Reference: 51574455
Brand: Helios
Reference: 51574452
Brand: B.I.G.
Reference: big00324
Brand: B.I.G.
Reference: osr64653
Brand: Osram