From the pattern:
A long line, loose fitting T-shirt with narrow contrast stripes carefully matched at side and sleeve and a simple, squared neck. It is worked in a medium weight cotton in half trebles.

Pattern calls for 16(17:17) 25g balls Main colour; 7(8:8) balls Contrast colour. Twilley’s Lyscordet is showing on Ravelry at 400 yards per ball.