What Is the name of this part?

[syndicate38]

hello guys, I want to ask about something
whether the name of the designated part of this red arrows? I want to buy it but do not know his name

sorry if this question has been asked before
thanks~

 

[88nightrider]

A: The bearing blocks? Might be another word for them
B: IDK

 

[Joe-405]

A is usually called a bearing cassette.

B is either the sprocket hub or brake disc hub. Without a larger pic of the whole axle i cant tell which.