These drive systems allow the shaft to pass through the centre of the socket.

• Pass-Through Socket Sets
• Vortex® Socket Sets

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.

This solves the occasional problem of a lengthy protruding shaft and even allows you to ratchet a nut along a threaded bar.