36t record quality inner ring will fit Campy CX or Campy Compact cranks. Interesting to note, the engineers at Campagnolo did more than just offer a chainring in a compact bolt pattern in 36t and call it a 'cross chainring. They actually beefed it up to with stand the abuse this particular aspect of the sport doles out on components - especially drivetrain parts. Black anodized finish is a nice touch cosmetically and adds a bit of durability as well.
The proprietary BCD, bolt pattern fits Campagnolo CX /Compact cranks only. They will not fit any other manufacturers compact cranksets.