just to share this UN blue czech vz 53/80 helmet ,i notice the inner rear of the shell is stamped 31 ,batch number maybe? and also i notice its devoid of the czech acceptance crossed swords so another theory could be allthough czech manufacture perhaps slovakian issued ,this theory is slightly flawed as the liner is dated 1986 and i know the dissolution of czechoslovakia took effect in 1993 but you never know ,be great to hear your thoughts on this one UN vz 53/80UN vz 53/80UN vz 53/80UN vz 53/80UN vz 53/80UN vz 53/80UN vz 53/80