Double ended box spanners are thinner than a socket and are much longer so that they can be used to loosen or tighten bolts and nuts in narrow recesses, meaning that they are often used in plumbing maintenance and automotive repair. This tubular box spanner is made from bright plated steel and able to accommodate a tommy bar.The Melco TIM3 ISO Metric Box Spanner is made with 3mm steel and has the following specification: Size: 7 x 8mm.Length: 100mm (4in).Additional Information:Box Type: Metric Box SpannerSize 1 (mm): 7Size 2 (mm): 8Length (mm): 100Tommy Bar: T31