http://cgi.ebay.ca/Shimano-Deore-6-S...item3a612820f8

It is hard to quantify, but these are precisely 27,000,000 times better than the plastic ones and work with both 6 and 7 speed. If you find some 7 speed ones they work with 6, 7, 8 speed. I think Shimano stopped making them because not enough people were buying replacements.