This is a great time saving device. Take twenty minutes or so to learn how it works and you will never transfer ribbing stitches to the main bed one at a time anymore. This is a very sturdy solid carriage with very few moving parts so very little can go wrong.
This does not include the manual, but the manual can be dowloaded for free. There are also several videos on youtube on how this is used. I have personally tested this on my 890 and my 910 and it works perfectly.
Item shows slight cosmetic wear but nothing that will affect its use. Please see pictures.