You will need 4 buttons. Sirdar used their buttons #B5611-0785

Finished measurements:
Chest circumference: 45.75(50, 54.25, 58, 62, 66)“ 116(127, 138, 147, 156, 167) cm
Finished Length: 25.25(26, 26.75, 27.5, 28.25, 29.25)” 64(66, 68, 70, 72, 74) cm
Sleeve length to armhole: 17.25(17.25, 17.75, 185, 18, 18)“ 44(44, 45, 46, 46, 46) cm

Yarn used:
Sirdar Saltaire
Shade 304 Stag - 8(8, 9, 10, 11, 12) balls