I'm just guessing here . . . but am thinking maybe they're made for very large (wide) pieces. As the stitches build up, they could slide along the cable, allowing the needle to hold more. As they're removed, they would slide back onto the "needle" section. The circle would be to keep them from sliding off. Like I said, it's just a guess . . . . I'm a crocheter but have used cabled hooks, for "longer" double-ended hooks (cable between the two ends), and know those cable can hold LOTS of stitches.