You may know my Jackie Lumber - Jack is her counterpart!
Jack was intended to be Jackie’s male counterpart and thus uses CYC standard men’s measurements. BUT … he’s actually a unisex piece. 
Jack is worked with 4-6” positive ease, depending on size.
Sizes are:
S (M, L, 1X, 2X) / 36 (40, 44, 48, 52)“ Chest
Garment is worked with two colors in intarsia method with yarn held double.
Suggested yarn: MillaMia Naturally Soft Merino
Yarn weight: yarn held together
Sport
+ Sport
= Worsted (9 wpi) 
 
Hook size: 5.0 mm (H)
Yardage: 3836 - 5754 yards (3508 - 5261 m) [depending on size]
Sizes: Small - 3X
Crochet terminology: US
Pattern Language: English