Chainrings - Shimano A or B type ???

[Commuter]

I need a couple of chainrings - The website offers Shimano A or B type

What is the difference ??

 

[TheDoctor]

I think it's referring to the 42T or so ring and there's different ones for the inner of a double, or the middle of a triple. Does the Shimano website have labeled diagrams of your chainset?

 

[mickle]

Read your old rings.