This is a Bowens UV Corrected Flashtube for the Esprit 250 and 500 Series Monolights. Its coating slightly "warms" the light output to ~5000° K.
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.