So far I do not know the model number for this ribber. But as manual for it is available online for free. It is possible that the model number of this ribber is Singer SR313 but I’ll need to confirm this info somehow. Although it also looks very similar to the Studio SR302 ribbing attachment. So, stay tuned!

It is a ribber for vintage machines Singer 312, 313 and 315 (Another ribber compatible with the same models is Silver SRN321 and Studio SRN321). This ribber is a standard-gauge with, very likely, 200 needles. The ribber carriage has a knob-like handle. It moves separately from the main machine handle, like many vintage ribbers do (for example, like a Brother KR580 ribber as shown in my video).

Because of the similarity between the machines, this ribber will very also work with Studio SK312 Cardmatic, Studio 313 Cardmatic, Studio 315, as well as Silver SK311 (card-matic), Silver SK312, Silver SK313 and Silver SK315 models.