Profile does make the heaviest clip-on's, but aerodynamics is more important than weight in the bike leg of a du or tri, so finding a set of clips-on's that you feel comfortable on is more important that how much they weigh.

Oval Concepts makes the lightest clip-on's. the A910's weigh less than 300 grams, but they're not for everyone. i used them for a few weeks, because they were the lightest i could find, but i eventually took them off because i just didn't feel comfortable on them...

the Syntace C2 Ultralite clip-on's are on sale at All 3 Sports, look into them, they're pretty light and everyone i know that uses them is comfortable on them...

http://www.all3sports.com/product_in...ralite-aerobar