You need a ceramic straightener which heats to 230°C The Silver Bullet Keratin 230 Straightener offers accurate, stabilised, variable heat up to 230°C which is a prerequisite of permanent and keratin straightening systems. The Keratin 230 is also ideal for medium to thick and difficult to manage hair. Features: •25mm ceramic/tourmaline plate surfaces - distributes heat quickly & evenly •Floating plate design - glides through hair like silk •Automatic cut out •Includes: a heat mat, crocodile clips, styling comb and paddle brush