This square was designed for Crochet For Kidneys Part 3, a charity project to make blankets for dialysis patients.

The Facebook group for Crochet For Kidneys Part 3 is here.

The squares can be worked as 13cm (as in the photos) or 15cm. Most charity projects require squares of 15 cm, but tensions differ, so an optional round is included to reach 15 cm if needed.