This is the standard clear, non-UV coated plug-in replacement flashtube for the Photogenic PL2500DR monolight.

Most current, professional flash heads and monolights are equipped with user replaceable flashtubes that may simply be plugged into, and unplugged from their sockets. With proper handling, these flashtubes may last for tens of thousands of flashes under normal use. UV copated flashtubes have a yellow appearance, and they counteract the excess blue 5700° or higher output of non-UV coated flashtubes. UV Coating lowers the color temperature to 5500°, which is the color of noon daylight on a clear day.