These are same as $200 R700 compact cranks except they have lighter 9-speed 50t ring instead of solid 10-speed ring. R700 weighs 870g with BB, so these should weigh less. Ebay seller has 165, 170, and 175mm length, but Shimano doesn't make 180's

With 110mm bolt circle and narrower road profile, these would be great for singlespeed or 1x9 bikes. Just remove the 50t ring and ride the 34t.

You can use Shimano, FSA, Token, and probably other BB cups.