About 6 mm wide ,this type of cord can be used to do the petals of flowers as is full but not to wide.
This cord is double, reported to the narrow one
Double cord 2:
First-Ch3 loose,
Round one: 1sc in ch2 from hook, 1 sc in ch3 from hook,
TL (turn left)
Round two: skip first ch,1sc in next chain ,both loops, 1sc in 2 edge threads,
TL (turn left)
Repeat round two to desired length.
The difference between cord one and cord two is the way you make the middle simple crochet (for cord 1-only front loop, for cord 2- both loops ). First one will make a rounder, full cord on the middle and the second one a cord more plate, but with same width (blue stripe in image is about 11mm wide).
Bellow is visible the difference between the cords. However both are easy and fun to make! Enjoy !