Shimano Ultegra® molded BR-6400/03 series brake shoes provide solid stopping power and long use for road cycling. •Weight - 52g •Material - Rubber/plastic Read More...
I bought these pads are a replacement for the original ultegra pads that came with my brakes. The originals had a metal body, these ones are plastic which must make them flex. Braking is pretty poor and a lot of pressure is needed to stop. My wife's bike has the same brakes with original pads and brakes much better even when I put my wheels on it. I would suggest looking for something with a metal body.
These took a while to bed in, which may be the reason for the previous comment. However I found that after a few rides they worked just as well sa the originals.