This drive system allows the shaft to pass through the centre of the socket. This solves the occasional problem of a lengthy protruding shaft and even allows you to ratchet a nut along a threaded bar. This also means you don't need to buy a duplicate set of deep sockets (which might not be deep enough anyway). These are physically identical to Ratchet Ring Spanners, so you won't need to waste cash on those either.

Bahco S140T Pass-Trough Socket Set, Multi-Colour, Set of 14 Piece
5.0

SATA ST09134SJ 21-Piece 3/8-Inch Drive Pass-Thru Socket Set, Metric/SAE, Polished, 10mm - 19mm | 3/8-Inch - 3/4-Inch, in Blow Mold Case
5.0