Sorry but LL65K T15 Lamp arc size and lumens are not specified is the main page.

Someone know what is arc size in mm and what is lumens for this lamp ?

The one I had, arc lengh was roughly 50mm

Lumenlab is selling t15 lamps with larger arcs now. A month ago I got a replacment, and the arc was fully 1/4 larger, even though this lamp also was labeled "corelvue 65k". I sent it back.

Got a comparison photo?

Also, unless you can see the electrodes, it's difficult to determine the actual arc length. The clearish portion of the arc tube is a rough indication of the lamp arc size, but it is not necessarily so.

Because of the nature of an HID light, for a given wattage and colour temperature, there are only a limited number of arc lengths and gas mixtures that will produce the apropriate colour temperature, lumen count and wattage. Generally if you alter one of those elements, the others have to change as well.

Therefore a 400W lamp with a 6500K colour temp at about 38,000 initial lumens must all have an extremely similar gas composition and arc length.

The arc on my bulb (and I believe all the ones LL sells now) is much longer than older ones that I have seen in plogs. And I do not think that the shorter are bulbs were Ushio bulbs either. I can't be sure, but the arc is a bit too long to fit in my standard triplet.

In my opinion the first one was a iwasaki lamp MF400/BD if Lumenlab kit have an external ignitor or MF400LE/BD if lumenlab kit use Mercury Ballast without external ignitor:

http://www.eye.co.jp/catalogue/index.html

or

http://www.atlantalightbulbs.com/ecart/nw0...S400DDUSHIO.htm

hum...it is not very honest all that..