B-Max2 wishbones

[Ashlandchris]

Last weekend I broke a rear wishbone so thought I'd better stock up. I notice that there are 2 versions of yokomo wishbone for both front and rear. These are called B2-008F or B2-008R (for front or rear) but then there is also the same with an "M" after the code and these are referred to as "medium".
My question is - what does medium refer to? Is it strength? Length? Flex?
I have ordered the standard wishbones, but was just intrigued by the option of something I have no idea what the difference is
Thanks