Differences between SFP-A and SFP-B
SFP-B TYPE:14x12x17mm/0.55x0.47x0.67in (LxWxH) Facing side is more like square.
SFP-A TYPE:15x10x12mm/0.59x0.39x0.47in (LxWxH) Facing side is rectangle.
SFP-B is a little big tight than SFP-A; SFP-A is suitable and flexible, SFP-B is durable and Tight. They are both fit in the slots of networking machines.