Per [1], the ESM/2s were only issued as part of the kit for the USAAF C-1 Emergency Sustance Vest, and packaged in a manila envelope. (ESM/1s were often packaged in a box) . The 4"x5" ESM/1 pictured here and the 3"x5" ESM/2 were both called out by the USAAF Spec 94-40653, the first as Size-20 (presumably, 20 sq inches), the second as Size-15. The USAAF issued ESM/1 had the spec number (40653) printed on them - those ordered by the US Navy did not. The ESM/1 designation came from the manufacturer (General Electric) and predates the USAAF specification. A brief history of the evolution of US military signal mirrors from the 1930s through the end of WW2 may be found online here: www.usmilitariaforum.com/forums/index.php?/topic/2412-wwii-emergency-signal-mirror/ [1] Clingenpeel, Justin, "Survival & Rescue Equipment of Word War II: Army Air Forces and U.S. Navy, Volume 2", page 93, top, (c) 2019, Elm Grove Publishing, ISBN 978-1-943492-61-9.

@@rafowell Scored the /2 as its the same version left behind by the crew of the lady be good. thanks for the informative reply. saved.

@@LBG-cf8gu ?! I thought the Lady Be Good was lost on April 4, 1943 [1][2]. I've seen no evidence that any of the services had even placed orders for the GE tempered glass mirrors before June 1943, let alone issued them. What evidence have you seen that the crew of the Lady Be Good had any ESM/2 mirrors? Here are some dates in the rollout of the ESM/1, ESM/2 mirrors: The sea trials of "the new tempered glass mirror developed by the National Bureau of Standards and manufactured by the General Electric Company" were conducted off Miami March 22-26 1943, and the report on the results was dated March 31, 1943, stating that while the test team had been dubious of the efficacy of the mirror, it had performed well, and recommended that a training film be commissioned. The minutes of the May 22, 1943 meeting of the multi-service "Liaison Committee on Emergency Rescue Equipment" recommended that "an information form for informing interested agencies that certain equipment be adopted" should be issued in the "very near future" for the "Rescue Signal mirror'. The announcement by the committee dated June 2, 1943 states "It has been established through laboratory and field test that tempered glass signaling mirrors are much superior to metal mirrors for rescue purposes. Two companies are now prepared to manufacture tempered glass signaling mirrors ... It is recommended that immediate steps be taken to procure such tempered glass signaling mirrors for the use of all airborne and Marine Services." The June 5, committee meeting minutes "authorized the Technical Aide to make definite arrangements through various procurement offices of the services for the purchase of the signalling mirrors through one service for distribution to all ..." The minutes of the August 2, 1943 meeting said that "a requisition from the AAF for 275,000 mirrors has already been received." [1]en.wikipedia.org/wiki/Lady_Be_Good_(aircraft) [2]books.google.com/books?id=cVUEAAAAMBAJ&pg=PA21

@@LBG-cf8gu One thing that can cause confusion is that the original designation of the General Electric ESM/1 emergency signaling mirror was "emergency signaling mirror No 2", which some might take to be a reference to the ESM/2. The official renaming of "emergency signaling mirror No. 2 as "ESM/1" was in the Sept. 1942 USCG bulletin [2] - so the "emergency signaling mirror No 2 was always a 4"x5" mirror. The designation on the mirror itself of ESM/1 preceded that announcment though - in this film, which I believe to be the one previewed by the ERE Committee on August 3, 1943[3], you can see the ESM/1 designator on the back of the mirror. [1] ======== ORIGINAL DESIGNATION OF 4"x5" mirror as "emergency signaling mirror No. 2" as of April 28, 1942 === babel.hathitrust.org/cgi/pt?id=mdp.39015021117927&view=1up&seq=177&skin=2021&q1=mirror " The following items of equipment for the better security of life at sea have been approved by the Commandant, United States Coast Guard, and published in the Federal Register April 28, 1943 : ... Signaling Mirror. General Electric Co., Schenectady, N. Y., emergency signaling mirror No. 2 (drawing No. 165-22-E-365 GE, dated March 1, 1943). [2] ========= OFFICIAL DESIGNATION CHANGE OF 4"x5" mirror to ESM/1 by September 1942 === babel.hathitrust.org/cgi/pt?id=mdp.39015021117927&view=1up&seq=213&q1=mirror CHANGES IN DESIGNATION General Electric Co., Schenectady, N. Y., has changed the designation of "emergency signaling mirror No. 2" to "emergency signaling mirror No. ESM/1." (The approval was published in the June 1943 Coast Guard Bulletin, p. 151.) [3] From the ERE minutes of August 12, 1943: "A preliminary showing of the instruction film on the signaling mirror, in preparation by Field Photographic of the OSS, was run off on Tuesday, 3 August, for the information of some of the people who attended the Special Meeting"

Here's an official US Navy photo released in August 1943 showing an ESM/1 being presented by the head of the ERE to a life raft survivor. www.flickr.com/photos/127906254@N06/32086664612 It's the earliest photo I've found of the General Electric "cross in glass" signal mirror.