Chainring in Dural aluminium 5083 BCD 110mm which fits to the compact crankset Shimano and Campagnolo.

BCD = draw a cirkel which runs through the center on all bolt holes and measure this diameter then you get the BCD also called ø measure.

If a chainring with 42 or less teeths it is for the inner position

If a chainring with 46 teeths or more, its the outer position