Actually a lot of metal and I used a metric equivalent 1/4” bolt. Regarding posts of better feel with the aero levers, I wonder if it is just the newer designs that deal better with the tight cable routing by having springs at both ends. My Miyata SLR 1050s were made both ways I think. The non aero is amazing, but the aero I’m sure is nice and perhaps nicer than many of the old non aeros. Apples to oranges I’m thinking.