Melco TM21 Metric Box Spanner 21 x 22mm x 82mm (3.1/4in) MELTM21

Thinner than a socket and are much longer so that they can be used to loosen or tighten bolts and nuts in narrow recesses.
Often used in plumbing maintenance and automotive repair.
Tubular box spanners are made from bright plated steel and able to accommodate a tommy bar.