The size is a medium.

“KY’s International Fashion Hawaii Hawaiian Camp Shirt Jeep Willys M Vtg Surf Board
EUC excellent used condition…NOT abused…see nothing wrong…see no holes, tears or stains
4 button front center closure
Black background with palm trees, surf boards and cars
Size and fabric tag are gone but guessing it is 100% cotton and about a men’s sz M
Machine wash

PLEASE check measurements with a similar clothing item you own for best fit.
All measurements are taken in inches…unstretched with garment lying flat.
Shoulders (shoulder seam to shoulder seam): 23
Chest (underarm to underarm): 29
Length (shoulder seam to hem): 30”

View all the information on eBay