There is no specific size advice for this item - just order your usual size.
Actual Garment Measurements
Size
S
M
L
XL
2XL
3XL
4XL
Chest
20
22
24
26
28
29
32
Body Length
26
27
28
29
30
32
33
Chest - Measured across the chest, one inch below armhole when laid flat.
Body Length - Lay garment flat (face down). Measure from the high point of shoulder from the back.