Stronglight chainring made from Dural 5083 machined alloy. Suitable for 8-10 speed setups. Can be used as an Outer or Inner ring. Compatible with Shimano 110mm BCD 5 hole or 130mm BCD systems. BCD (Bolt Centre Diameter) can be measured by taking the distance between two adjacent bolts. Compatible with 9/10 Speed Shimano/SRAM systems. Colour: Black. Material: CNC machined Dural alloy.