12W 1x12 add-on reverb unit that could be used with a companion amp.
Marks that can be entered for this maker: Serial number (plate), Transformer code.
Nothing predates 1963; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: Blue Book of Guitar Values — ampeg