It's a bulb for the Japanese market, I don't think you can get them in the 50% brighter type, Basically it's a H4 with some extra notches.
If you need spares you can get them from http://www.wemoto.com/
you wont get them local as they are unique to a few grey imports, i know a few lads that used to cut the bottom tags of and file a notch in a h4 and that seems to work. http://www.zxrworld.co.uk/zxr400/iridium.html