This 11-speed inner chainring is compatible with hidden or non-hidden bolt cranksets. Select 34t, 36t or 39t. The 34t is for a 110mm bolt circle and shifts best when paired with a 50t outer ring. The 36t is for a 110mm bolt circle and is best paired with a 52t outer ring. The 39t is for a 130mm diameter bolt circle and shifts best when paired with a 53t chainring.