KoltM3

Hey guys, just looking for some help with this. I bought a Hackva GM2608 goalie helmet quite a few years back to try playing in net. Long story short I no longer use it and it's just been collecting dust. I'm looking to list it on Sideline Swap and other marketplaces but I don't remember what size it is? I believe it's a junior but nothing beyond that, no indication on the mask from what I see. So whats the best way to determine this so I can accurately list it?