Singer SRP-50 Instruction Book page 4

Congratulations on your purchase of SRP-60 Ribber I!
This technologically advanced and sophisticated Ribber converts
your knitter into a double bed knitting machine, and will be sure
to enhance your pleasure in knitting.
With easy-to-follow instructions and diagrams, this book assists
you to familialize yourself with the SRP-50 Ribber before making
your first garment using the Ribber.