Silver Reed AG50 intarsia carriage is compatible with electronic Singer/Silver Reed/Studio/Empisal machines with the model numbers SK580 and SK840. It looks like a full-on carriage and, indeed, can work independelty not just for intarsia but to knit simple stockinet. Overall, it operates similarly to non-electronic intarsia carriages, i.e., the yarn should be laid over the needles in C position. Refer to the manual for further details.