I think I can just about read, "Resin Kit", written on the box. But they are a new company to me (and I think they are new to Tracks n Troops as well) so I don't know for sure.
Gramodels also make a FCM 2C. And I know for sure that that one is resin with metal gun barrel.
In truth I don't know. I was just browsing the sites of the manufacturers and sellers who are known to do WW1 stuff (W^D, Retrokits, Black Lion, Matador, Milicast, Ykreol, IT Miniatures, Solfig etc) and then started to look through lists of companies I'd never looked at (perversely, I couldn't sleep!). I hadn't seen 5M Hobby on Tracks n Troops before, so I gave them a quick glance.
While I've been typing this, I have found 5M Hobby's site: http://www.5mhobby.com/ but I can't see any other stockists.