Curling irons are heated tools with a metal barrel used to make curls or waves in hair. They come in different sizes and tips to shape tight ringlets or relaxed, beachy waves.
When I was in baseball and you went into the clubhouse, you didn't see ball players with curling irons. Red Barber
However, this fiber is sensitive to heat and cannot be styled with flat irons or curling irons. Source: Internet
Milland's hair was naturally straight, so the studio used hot curling irons on his hair to achieve the effect. Source: Internet