The COBRA Class 4 Premium package comes with all of the change over sets and accessories to sew from a #69 thread for upholstery to a #415 thread for extremely heavy materials. Yes, the ideal situation would be to have 2 machines, a flatbed for thread sizes up to 138, and a cylinder arm for 207 thread and heavier, but if you can only go with one machine, then always go for the cylinder arm because they are much more versatile. Thanks, Steve