ChiaoGoo 10 cm interchangeable needle tips for lace knitting are made of surgical steel. The needle sizes are engraved in the needles. The 10cm long interchangeable tips come in sizes 1.50mm - 10.00mm. All TWIST & SPIN tips, cables, and accessories are interchangeable! Most ChiaoGoo TWIST & SPIN items have the code [S] for the small screw size and code [L] for the large screw size. Items with code [S] are interchangeable with other items with code [S] and tips in sizes 2.75 – 5.00 mm. Items with code [L] are interchangeable with other items with code [L] and tips in sizes 5.50 – 10.00 mm. The screw sizes (S or L) are engraved in the tips; this type of size indication of the cables and accessories can be found in the item numbers.