From the pattern description

This pattern of circles within stripes is clearly defined when worked in a smooth, regular yarn such as this cotton/wool blend. You can adapt the design to make a fabulous matching throw in a single color. Work six design repeats across the width and repeat the whole chart twice lengthways; this would require 12 50g (1 3/4 oz) balls of yarn. Finish the edges with ribbon, mitered at the corners.

Finished size - 18 inches square

Pattern calls for -
4 x 50g (1 3/4 oz) balls of cotton/wool yarn in pale green (A)
2 x 50g (1 3/4 oz) balls of cotton/wool yarn in violet (B)
Sewing needle & pins
3 buttons
18 inch square cushion pad/pillow