hello there lads , got a little silly question , i bought recently a full face respirator called Panarea 7000 , with a2b2e2k2 , its threaded for rd40 x 1/7 filters . the question is , can i plug 40mm standard nato filters into that kind of thread ? if not , should i get a replacement mask , or stay with the one i got ? its brand new BTW , filter too .