▁kn ob ▁at ▁the ▁other ▁end ▁to ▁prevent ▁st itch es ▁from ▁sli pping ▁off . ▁Such ▁need les ▁are ▁usually ▁ 1 0 - 1 6 ▁inches ▁long ▁but , ▁due ▁to ▁the ▁compress ibility ▁of ▁kn itted ▁fab rics , ▁may ▁be ▁used ▁to ▁kn it ▁pieces ▁significantly ▁wider . ▁ ▁The ▁most ▁important ▁property ▁of ▁need les ▁is ▁their ▁diameter , ▁which ▁ranges ▁from ▁below ▁ 2   mm ▁to ▁ 2 5   mm ▁( rough ly ▁ 1   inch ). ▁ ▁The ▁diameter ▁affect s ▁the ▁size ▁of ▁st itch es , ▁which ▁affect s ▁the ▁gauge ▁of ▁the ▁kn itting ▁and ▁the ▁el astic ity ▁of ▁the ▁fabric . ▁ ▁Thus , ▁a ▁simple ▁way ▁to ▁change ▁gauge ▁is ▁to ▁use ▁different ▁need les , ▁which ▁is ▁the ▁basis ▁of ▁une ven ▁kn itting . ▁ ▁Although ▁kn itting ▁need le ▁diameter ▁is ▁often ▁measured ▁in ▁mill im eters , ▁there ▁are ▁several ▁different ▁size ▁systems , ▁particularly ▁those ▁specific ▁to ▁the ▁United ▁States , ▁the ▁United ▁Kingdom ▁and ▁Japan ; ▁a ▁conversion ▁table ▁is ▁given ▁in ▁the ▁kn itting ▁need le ▁article . ▁ ▁Such ▁kn itting ▁need les ▁may ▁be ▁made ▁out ▁of ▁any ▁materials , ▁but ▁the ▁most ▁common ▁materials ▁are ▁met als , ▁wood , ▁b am bo o , ▁and ▁pl astic . ▁ ▁D ifferent ▁materials ▁have ▁different ▁fr ict ions ▁and ▁g rip ▁the ▁y arn ▁differently ; ▁s lick ▁need les ▁such ▁as ▁met all ic ▁need les