Source Four PAR Electronic Theatre Controls / ETC
From the ETC website:
"Elegant, compact, efficient and flexible - the new standard for PARs. Source Four PAR comes with a set of four snap-in lenses that mount in a cool, rotating ring. That also means no more reaching into a hot can with cracked porcelain sockets. And when you need a new lamp, just use your stock of Source Four HPLs (no need to carry a large inventory of expensive PAR64 lamps). The Source Four PAR's compact design means more units can be mounted on a pipe or fit into a truck. Combined with reductions in power and cable requirements, Source Four PARs are perfect for touring."