WEM made an instrument cab which they called a Starfinder 100 Twin. This cab was designed mainly for bass but WEM also produced a version of this cab for PA use. They were usually sold in pairs as part of an X29 stack but they could also be purchased individually. Each cab contained a pair of 6 ohm drivers wired in series to give 12 ohms so a pair of cabs would give 6 ohms in total which was the standard output impedance on many WEM amps such as the PA100. The main difference between the instrument and the PA cabs was that the instruments cabs were 6 ohms and could therefore be used individually with WEM amps and the drivers in the PA cabs were twin cone, which was considered to be better for PA.
The following pics show a pair of PA 2×15″ cabs which I acquired in January 2020 and which are undergoing refurbishment.
One cab done, other one still to do –
Both cabs now fully refurbished –