TWM is at the "top" of the ITB game, but are DEF not the most affordable --> http://www.twminduction.com/Home/Home-FR.html

Redline, lesser known but decent product --> http://www.redlineweber.com/html/thr...side_mount.htm

Jenvey (s2000 ITBs put them on the map in the US, but they were always on the map overseas) --> http://www.jenvey.co.uk/

ALSO Asport makes some nice ones (48mm)... I can't remember their site though. Am I leaving any of the major players out? And you can also make your own!!