These rods narrow n the middle for a tighter curl and are made of durable plastic to last a long time use again and again for flawless curls. Yellow 5/16 Inch (item# 292538) Blue 3/8 Inch (item# 292537) Pink 7/16 Inch (item# 292536) Gray 1/2 Inch (item# 292535) White 9/16 Inch (item# 292534)