THE FRAME MUSHROOMS ARE MADE FROM HIGH DENSITY ACETAL AND COME COMPLETE WITH A M10 X 1.50 BROKEN BOLT (WILL NOT JUST BEND). ACETAL MUSHROOM SIZE 50MM DIAMETER X 145MM MAX LONG. NO MODIFICATION IS NEEDED TO FIT THESE CRASH MUSHROOMS. Just writing to say how good the mushrooms were at protecting my bike!It was a fairly low speed compared to diesel, about 25 mph, and the mushrooms did a really good job! All I had to replace was brake levers and an indicator, it would have been much worse if there hadn't been protection. I was a little worried about the quality because the price is so cheap, but I'm totally impressed and I r.