This 250 watt quartz halogen modeling lamp provides a brilliant light output to help the photographer pre-visualize the scene that the flash illumination will create. The 4108 is the replacement modeling lamp for the 2103-FC Fan Cooled Bare Tube Flash Head and M300,M500,and M600 Fan-Cooled Monolights. It perfectly nestles into the center section of these units' custom made flash tubes. Due to the heat that this lamp creates,it should not be used with the Novatron lighting instruments that are not fan-cooled. Some users find the modeling lamp to be bright enough to use as an incandescent light source,to warm an image,at slow shutter speeds,in conjunction with the flash,or to even use in some video applications.