This is a 520 Renthal Ultralight Aluminium Sprocket which as 66% lighter than steel

Renthal's hard anodised rear chainwheels are specifically designed for road and road racing applications and add increased wear resistance.

They are CNC machined from the same 7075 T6 material as  the Renthal off-road chainwheels, yet feature the increased longevity from the hard anodising process.

Hard anodising is an integral surface coating which significantly increases the hardness and wear resistance of the chainwheel surface.

520 Pitch