Is the Glock Sport Combat Holster reliable enough for CCW?

This: http://ift.tt/2tgRrEH want to use it as an OWB holster concealed under a t-shirt and I have their Glock brand magazine holder which isn't bad but if the holster is made out of the same material maybe it's a little flimsy for holding a Glock 19? via /r/CCW http://ift.tt/2sH8RNR