Momo Handbrake Boots/Adapters - which size fits FTO??

[peterm3150]

On eBay, there are lots of different sizes of MoMo handbrake boots. (C2, C3, C8 etc.) Does anyone know which size fits FTOs the best?

Also, if you search eBay for MOMO HANDBRAKE, there are also lots of different "adapters" for sale labelled A3, A4, A7 etc.
(example of listing - http://tinyurl.com/ydjfg6t)
What are these for and if they are needed which is for FTOs?

Thanks.
Pete