The pattern name says it all.
This sweater has T-bone on its back.
The horizontal line is I-cord and the vertical one is 3 needle bind off in a contrasting colour.
Back and front panels are worked flat separately until they are joined at underarm, then the body is worked in the round. The sleeves are picked up around armholes and knit in the round.
The pattern includes photos and easy to follow.
2 extra needles are needed for 3 needle bind off.

Size Measurements (1, 2) 3, 4:
Bust: (115cm/45.3”, 128cm/50.4”) 146cm/57.5”, 164cm/64.6”
Upper arm: (33cm/13”, 36cm/14.2”) 40cm/15.7”, 44cm/17.3”
Recommended positive ease: 20cm/7.9” to 30cm/11.8”

Yardage:
MC: (1070m/1280yards, 1194m/1306yards) 1360m/1487yards, 1525m/1668yards of worsted weight yarn
Turtle neck requires extra (66m/72yards, 66m/72yards) 72m/79yards, 74m/81yards of MC yarn
CC: 30m/33yards of worsted or aran weight yarn

Needles and Tools:
4.5mm and 4.0mm 60cm/24” or 80cm/32” circular needle
4.5mm, 4.0mm DPNs or short circular needles (for sleeves)
4.5mm 40cm/16” circular needle (for neckband)
Stitch markers, tapestry needle and stitch holders or waste yarns
2 extra circular needles. The length must be 80cm/32” or longer and size must be 3.0mm or smaller

Gauge:
18 sts / 28rows = 10cm/4” in Stockinette Stitch on bigger needles after blocking