The Trestle crank is built around 100% post-weld, heat-treated 4130 chromoly and a 24mm hollow heat-treated spindle. Heat treating, although adding an extra cost, makes your parts less likely to bend or break and it's clear to see Premium have made this of upmost importance. You never really want to stick a set of new cranks into an old BB, to avoid this Premium Included a Mid BB, crank removal tool, and all the hardware needed for a completely fresh drivetrain. A rounded spindle boss eliminates sharp edges where it matters avoiding that nasty ankle bite all of us dread. What's interesting about this product is that's only available in a 165mm length, it's a bold step in providing only what the rider wants instead of a bunch of different sizes. 165mm is becoming increasingly popular as folk look to get an ever more responsive bike. To top it off Premium are backing this product with a lifetime warranty, always a good purchase incentive for those who are the harshest on products.