Red army gas mask BN-T5, with the MT-4 filter

RKKA gas mask BN-T5, with the MT-4 filter.  As can be seen from the photos, the filter and mask are stamped with the same serial number. The filter was produced in 1941, August. The gas mask was tested and approving markings were made on January 2, 1943, and it got serial number M4309.  The next check was carried out in 1945, and the check markings are indicated both on the mask and on the filter.  The bag was issued in 1941, as evidenced by the markings on it. The set is unique and never used, in condition as has been stored in stock, such a "time capsule". The exception is slight moisture damage on the bottom of the filter.but in general it's a great set in good condition.