Shimano cranks are all identified with model information above or surrounding the area on the backside of the pedal threads. For example; FC-6700/6750 = Shimano Ultegra. The crank length is often located in the same area, which is helpful to note before placing an order. This is a number between 165 and 180mm and will always be listed on the arm.
SRAM, Cannondale and FSA cranks are branded with their model name (usually on both the drive side and non-drive side) and may not have a model engraved into the crank arm itself.
If you're unsure about how to identify your specific crank, you can snap some photos of both sides of the crank and write down any information written on the crank itself and we can help you identify if you have a compatible crank model. Email information or photos to us by submitting a new help ticket to Stages Cycling or Stages Cycling Europe or bring your bike in to your local Stages Cycling dealer for help.