"I have a cheaper Bahco set it was about £20 back in 2021 not sure why this one is so much more expensive.
Not sure what they/yoou mean by "pass through" ?"
Both the socket and it's drive are hollow Ted.
Describing my set ... the sockets are driven by external hex (19mm think ) rather than 3/8 etc square, with the extension bar hollow too.
Think they were originally for "stud" work so you could slide the assembly over long bolts rather than need "deep" sockets.
Coincidentally, they can be arranged to make very competent plug spanner (plug top just goes inside the extension bar) and seem to fit into various cylinder head recesses easily, while not having too high bulk around head to prevent competent alignment etc.
By no means essential, but do work in quite severely restricted installation .... in some cases.
Mine also with "Swan neck" gentle curve in ratchet handle that gives very shallow stack height, guess low profile would be good description, but also flips over to place the handle up or down in relation to surrounding frame bits etc.