Twist tips are made of surgical-grade, stainless steel which means there is little to no chance of allergic reaction, no corrosion, no discoloring and NO smell. The size is laser imprinted on each tip. Twist tips can be used with Spin nylon and Red cables. All small & large TWIST & SPIN system tips, cables and accessories are switchable! Large tip to small cable adapter available for separate purchase. Most TWIST & SPIN parts and pieces are coded [S] for the small diameter screw size and [L] for the large diameter screw size. Within the TWIST & SPIN systems, parts coded [S] are compatible with other [S] coded parts and tip sizes US2 (2.75 mm) through US8 (5 mm). Parts coded [L] are compatible with other [L] coded parts and tip sizes US9 (5.5 mm) through US15 (10 mm). Product image shown covers a range of needle sizes. Item code 7504.