Red Box is a rectangular turtleneck sweater with a very wide body and fitted sleeves. It comes in two sizes:

S/M/L:
Body circumference: 140 cm (55 1/4 inches)
Sleeve circumference at top: 31,25 cm (12 3/8 inches)
Sleeve circumference at cuff: 20 cm (8 inches)
Sleeve length: 40 cm (15 3/4 inches)
Body length from under armhole to hem: 36 cm (14 1/4 inches)
XL+:
Body circumference: 160 cm (63 inches)
Sleeve circumference at top: 38 cm (15 inches)
Sleeve circumference at cuff: 24 cm (9 1/2 inches)
Sleeve length: 35 cm (13 3/4 inches)
Body length from under armhole to hem: 36 cm (14 1/4 inches)

Red Box is worked top down from the shoulders in stockinette stitch, shoulders are shaped by increases at each side of the three stitches shoulder ridges.

Front and back are joined under the arms and the body is worked in the round to the hem. Body length is easily adjustable.

Sleeves are picked up from the armholes and worked in the round to the cuff.

Stitches for the turtleneck are picked up around the neckline. After working 50 cm (19,7 inches) the turtleneck is folded to WS of work and sewn to the neckline.

Many many thanks to my fabulous test knitters comnurse, MrsLis and ToneCecilie!