This is a Dynalite #4006C Clear Flashtube for the SH4000 and 4080 flash heads. 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.The glass dome provides protection from contact with fingers and studio equipment.