The standard projection optics can be replaced by the Tele Booster if the range is too small or a smaller image is desired. The Telebooster is completely screwed onto the projector. The gobo has an outer diameter of 37.5 mm and an image size of 20 mm. Gobos in PHOS standard sizes (50 mm / 40 mm) can not be used. The Telebooster is compatible with all versions of PHOS 25 - 85 and the 85 mm standard lens. Not suitable for PHOS mini and PHOS 20.