What is the center back length of this jacket, size small or medium?

Tech Specs:

Material:

[membrane/laminate] Gore-Tex Performance Shell (2-layer); [lining] taffeta 

Insulation:

PrimaLoft Eco (60g) 

Fabric Waterproof Rating:

guaranteed waterproof 

Fabric Breathability Rating:

guaranteed breathable 

Hood:

yes, fixed 

Length:

hip 

Venting:

underarm zips 

Powder Skirt:

yes 

Pockets:

(external) 2 hand, 2 chest, (internal) 1 media, 1 goggle 

Seams:

fully taped 

Wrist Gaiters:

yes, Lycra 

RECCO:

yes 

Recommended Use:

skiing, touring 

Manufacturer Warranty:

lifetime