The round plastic rings in 2 sizes are slipped on the needles to mark the beginning and ending of pattern stitches, increasing or decreasing on the garment. 30 each in a package (blue and pink assorted) 10 small & 20 large. Suitable for 2.0mm to 4.0mm (small rings) and 4.0mm to 6.0mm (large rings) knitting needles.