Big board, bigger than a hex width Unibus board IIRC. Seems to be in decent condition, core plane looks good despite the protective plastic cover having been removed. It's manufactured by Singer Business Machines and has several prototype designations on the board (Dymo label visible in the picture, and a few "PROTO ONLY" labels in copper on the carrier board). The core plane plugs into an edge connector and is removable. Aside from the actual core, it also contains some sort of IC made by Ampex, don't know if they're sense amps or what.
Anyone interested in it?