Back in December 2024, a seller on Gunbroker listed two 50 round Sterling magazines. They appeared to have been originally made as extended magazines, not two magazines cut and shut together.

The magazine bodies were of typical four part Sterling/Patchett design, with a roller follower. There were two witness holes on the underside and three witness holes on the upper face. There were no markings on the spine or on the bodies with the exception of 45 which was etched (engraved?) alongside one of the witness holes.

The attached photo is screenshot from the seller’s listing.

Does anyone know anything about these 50 round magazines?