To keep track in your knittingwork.
If you have to count your rows (with lace, cable or whatever counts)
Hang it on your needle, and slip it trough the first ring,
next row (or patternmove) trough the 2nd etc. etc.these goes up to 5 rings.
suitable for needles 1,75mm, 2 mm, 2,25 mm and 2,5 mm
Buy them here
Of op de Handwerkbeurs natuurlijk!