"Pilots, Man Your Planes!"   
                                         WWII U.S. Naval Aviation Collector's Guide                                                                              
The Aviators' Summer Helmets, Pt 2   
As seen above, it was very common for individual members of the same squadron to exhibit a variety of flight gear and clothing. Functionality was important, but uniformity was not a requirement, therefore, personal taste and comfort took presidence. All seven of these VMF-214 pilots* are using the M-450 summer helmet, but no two are exactly alike.

The following photos are provided to expand on the information given in the table on the first page of part one of this article in hopes that it will help you to identify variations of the summer helmets without having to see, or read, their labels. At the same time, we will take the opportunity to illustrate some of the common types of earphone holders that you will see in vintage photos and find on surviving examples of these helmets.
Above:  This example of an H.L.B. Corp. M-450 is from a recently discovered contract, Nos.-96014. Construction details are unremarkable, other than it having "Anchor Brand" manufactured chin cup buckles, distinguishable by the company's trade mark, a small anchor, cast into the rear surface of each buckle. Their products appear on many items of U.S. military equipment of the era, and are sometimes mistaken by collectors today as an indication of U.S. Navy use, but it is not.

Below:  Another example of a helmet with unconventional buckles. This B-G Inc. M-450 had its label removed when the leather ear cups / powder puffs were installed, so we cannot tell which of their two contracts it is from. All other construction details are as expected, but the buckles are a non-standard, concaved type we have not encountered before. This interesting variation is from the collection of "Goz".

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Above:  A B-G Inc. M-450 with narrow edge tape and chromed, convex buckles. The earphone holders and chin cup are the frequently encountered tan leather.

Below:  Another Slote & Klein NAF-1092S with the same features noted above. Different here are the earphone cups, which are covered with tan fabric. The reason for this variation is unknown.
Above:  An interesting H.L.B. Corp. M-450-1, contract number NXS. 1020. This example has the dark-finish buckles and has been fitted with dark brown earphone holders, as supplied with the brown leather NAF-1092 intermediate flight helmets.

Below: The dull gray buckle of this B-G Inc. M-450, contract number NXS-1008, stands out, as do it's red rubber TC-66 earphone holders. These were apparently a field-expedient fitted to many helmets as a remedy to the uncomfortable combination of internal powder puff and external leather earphone holder that was the standard for Navy flight helmets at the time.
Above:  As seen on this H.L.B. Corp. M-450-1 (Contract NOS. 1020A), another common method of attaching the TC-66 cups, rather than stitching them directly to the helmet, was to secure them with a chamois cover, which was machine-sewn in place. A variation of the TC-66, made of black rubber, was also used.

Below:  The Navy's official replacement for the leather ear cup / powder puff combination was the "Earphone Receptacle", stock number (R)16-R-0439, contract number N288s-9336. Their stated purpose was to "provide both ear comfort and improved radio reception." Due to their distinctive shape, collectors now refer to them as "volcano" ear cups. They are seen here on a B-G Inc. M-450.

Above:  A Mirabelli produced M-450, easily identified by the external seam re-enforcements and dark, concave wire buckles. The leather earphone holders are a chocolate-brown color, typical of pre-war manufacture.

Below:  This Slote & Klein NAF-1092S has wide edge tape,  buckle re-enforcement that covers the edge tape and chromed, concave buckles. The earphone holders and chin cup are the shade of leather known to collectors today as "oyster gray". 
Above:  Reflecting the rapid developments in technology brought on by the demands of war, the M-450 helmet, and it's various methods of earphone attachment, were soon to be replaced by the improved AN-6540 series of flight helmets which featured factory-installed earphone receptacles. This new design consisted of a rubber earphone socket fitted with an internal sealing member, or "doughnut", of chamois-covered kapok. Many M-450 helmets already in service were modified by mounting the version of this assembly made for use with radio headsets. This  H.L.B. Corp. M-450-1 has been so fitted.

Below:  An anomoly, as shown here, is the H.L.B. Inc. M-450 produced under contract number N156s-18358. For reasons unknown, this example is fitted with smaller chin cup buckles than the other H.L.B. helmets. The inside width of this buckle (where the strap passes through) is only 5/8", whereas the full sized H.L.B. buckle, found on their other helmets, is 13/16" wide. Due to this difference, some chin cup's straps are too wide to be used with this helmet.
Above:  This H.L.B. M-450 is from the 10th (and most recently discovered) contract we have found to date, N156s-18833. A salty (and oily) old sea dog, it shows signs of many flight hours in an open cockpit with the heaviest staining at the rear. We will venture to guess this is an indication it was worn by one of the valiant rear-seat men who "flew backwards into battle".

Below:  A Slote & Klein NAF-1092S, this time with brown foam rubber ear cups of the type often found on USAAF radio headsets. These were probably "borrowed" from Air Corp stocks at a location where the services operated in close proximity to each other. A ring of chamois has been machine stitched to secure them to the helmet.
Above:  Another example of a Mario G. Merabelli produced M-450, easily discernible by its exterior seams and dark buckles. What makes this one stand out is the very dark shade of gray finish on the leather ear cups.

Below:  The interior label has been removed on this example, along with circles of fabric where the cups are installed, but we can still tell it is an M-450 made by B-G Inc. by its distinct exterior features. Here, we find a variation of the TC-66 rubber ear cups, being held on by rings of hand-basted chamois. Made of black rubber, they are identical to the red rubber version in size and molded surface markings, but the contractor's part number is ink-stamped in white, rather than black. It is believed that these were produced of a more stable compound than found in the original red cups, which tend to "melt" under certain atmospheric conditions, and who's gray rubber inner rings are prone to becoming hard and brittle.
Above:  Another example of chamois being used to secure the headphone receptacles to a Slote & Klein NAF-1092S. In this instance, it holds the large rubber external half, while the interior "doughnut" is mounted with adhesive cement.

Below:  This H.L.B. Corp. M-450 has had a circle of fabric cut away on each side and TC-66 cushions mounted from the interior. Chamois covers have been hand stitched over the protruding portion of the TC-66 cups and the TH-37 ear phones, holding the components in place. 
*Publicity photos of the VMF-214 pilots were taken showing them in groups based on the location of their home towns. Areas included were, New England, Pennsylvania, Chicago, etc. This group is the "Yamheads". An affectionate term used, at the time, to denote anyone from the Southern part of the United States. Standing, left to right, are Burney Tucker, Rufus Chatham, Harry Johnson and Gelon Doswell. Seated on the Corsair's wing are John Bolt, Donald Fisher, James Reames (the squadron's Navy flight surgeon) and Denmark Groover.
Below:  A similar helmet, by B-G Inc., with the label intact. In this instance, the helmet's material was not cut and the entire rubber cup is sandwitched between the chamois ring and the fabric of the helmet. This causes the cups to protrude from the side of the helmet about a half inch further on each side, when compared to the example above where a hole was cut out for the cups and they would make contact with the wearer's skin.