Surly’s Stainless Steel Chainrings last longer than their aluminum brethern because the 304 grade metal they use is 35% stronger. The rings aren’t pinned or ramped so when one side starts to wear you can flip it around and pedal some more! They work great with singlespeed, fixed, and 1×9 applications, and the teeth are 2.1mm thick so they work well with 9-speed chains.