Original issue, US Army Technical Manual, 192 pages, size is 5 1/2" x 4", stapled, 31 August 2010.  This not a commercial copy or print but an original issue government print issued in 2010 and republished in 2011.  This publication is titled - TM 3-4240-346-10, Operator's Manual for Chemical-Biological Mask: Field, M40A1 (Small, Medium,  Large);  Chemical-Biological Mask: Combat Vehicle, M42A2 (Small, Medium, Large).  Publication is designed to provide information and instructions for the use and operation of these masks.  Very well illustrated using detaied and clear line drawings.