BA spanner and socket set the set. Covers sizes between BA0-BA 11 17pc Additional Information 6 x Mini Double open ended spanners 0BA x 2BA, 1BA x 3BA, 4BA x 6BA, 5BA x 7BA, 8BA x 10BA, 9BA x 11BA. 11 x 1/4\"D BA Sockets: OBA, 1BA, 2BA, 3BA, 4BA, 5BA, 6BA, 7BA, 8BA, 9BA, 10BA. Manufactured from Chrome Vanadium. This new BA socket and spanner set (part number 7132) covers the most commonly used sizes. BA (British Association) screw thread sizes cover a range of small screw thread, originally being specified at the end of the nineteenth century as the British standard fastener for small electrical devices and scientific equipment. The design of the BA thread profile lends itself to low-torque applications. They are used for miniature instruments, clocks, optics, moving coil meters, conduit boxes, micro applications and modelling. BA fasteners can still be found on classic cars right up to the early 1970s on speaker enclosures and instrument panels. This useful set from Laser Tools incudes 11 1/4\"-drive sockets manufactured from tough chrome vanadium steel: OBA, 1BA, 2BA, 3BA, 4BA, 5BA, 6BA, 7BA, 8BA, 9BA and 10BA. The six open-ended spanners are sized at 0BA x 2BA, 1BA x 3BA, 4BA x 6BA, 5BA x 7BA, 8BA x 10BA and 9BA x 11BA. Packed in machine-cut EVA foam to keep the tools secure and to fit neatly in the tool box tray.