Here is a GE 400W Lucalox twin arc tube standby HPS lamp.
Manufacture date: Nov 2000
Colour temp: 2100K
Lumens: 45000
Base: Mogul E39
Lamp shape: ED18
Made in: USA
Lamp life: 40000 hours
Frederick, Maryland is full of those standby lamps in different wattages! So far I have seen Sylvania branded ones in use with ET-25 shapes for 150 watters and as well as the larger ones
All the Best
COlin