Box spanners are thinner than a socket & are much longer so that they can be used to loosen or tighten bolts & nuts in narrow recesses, meaning that they are often used in plumbing maintenance & automotive repair. This tubular box spanner is made from bright plated steel & able to accommodate a tommy bar. Size 9/16 x 5/8 Whitworth Double Ended. Length: 6 in. 150 mm.