What is the difference between the WFM7HD+ WFM7A and WFM7M modules? What do these modules give you?

What is the difference between the WFM7HD+ WFM7A and WFM7M modules? What do these modules give you?

Each of these modules corresponds to the functionality of its respective WFM700 model (A, HD or M) and adds two additional SDI inputs of that type. In other words, the WFM7A module would add two additional SDI inputs with the same capabilities as a WFM700A instrument (standard or high-definition), the WFM7HD module adds two additional SDI inputs for high-definition only use and the WFM7M module adds two additional SDI inputs for SD or HD with Eye, jitter and data measurement capabilities.

It is important to note that these additional inputs do not allow you to monitor multiple inputs simultaneously; you must still select one of the inputs to process at a time. The additional module simply doubles the number of inputs you can switch between or can add functionality to a lower end (HD or A) model WFM700.