What is the sizing? S or M?

Grabbed this off the rack and saw that the hanger said "S". After trying it on at home it fits a little bigger than the piece i tried in S (I tried on a blue piece in size S, but i swapped it for this black piece). Can someone let me know if this is size S or M? Item code GK9651. It's a tracksuit set - a jacket and a pair of pants