The M1931 liner was secured to the helmet shell with three retaining rivets.  These rivets (Splinte) were positioned on the shell with two located on the front of the helmet (near the temples) and one rivet centered squarely on the back.  The rivets featured a round, semi-domed head with two prongs which were secured by a flat washer.  When attached to the helmet, the rivet’s prongs were inserted through a pre-drilled hole in the shell, and passed through the outermost ring of the helmet liner.  The flat washer used to secure the rivet to the helmet contained two rectangular slots.  Once the rivet was inserted through the helmet shell, the two prongs were drawn back and flattened.

Initial specifications called for the rivets to be manufactured out of four separate parts which included the domed rivet head, a solid metal base to which the head was crimped, the prongs, and finally the retaining washer.  The entire rivet was manufactured of brass and then zinc coated by galvanization to prevent the green corrosion that typically collects when brass is exposed to moisture.  Six firms were contracted to manufacture the rivets.  These manufacturers were responsible for producing the rivets, painting them the appropriate colors, and packaging them for shipment to helmet production facilities. These six firms were the only manufacturers involved in the production of liner retaining rivets through May 1945.  Each of the firms was required to place a maker mark on one of the two prongs on each of the rivets.  This practice was not fully adhered to during early production. Helmets with components dated 1937 and earlier often have unmarked rivets.

The first M1935 helmets assembled received brass rivets with zinc coatings as previously described.  The majority of these helmets were shipped first to the Luftwaffe and then to the Army.  On 14 May 1936 the Luftwaffe issued an official bulletin citing the brass retaining rivets as insufficient to hold the weight of the helmet when hung by the chinstrap or under severe impact.  The apparent softness of the brass sheeting resulted in the shearing of the rivet prongs.  As a result, the manufacturers involved gave a new supply of rivets to the Luftwaffe.  The Luftwaffe received the majority of helmets from the Thale plant in the early part of 1936.  The Army received its first large order of helmets on 30 April of the same year.  This was just one month after the Luftwaffe had officially noted the shearing problem.

The shearing problem resulting from the brass sheeting used in the manufacture of the helmet rivets was eventually corrected.  Steel rivets galvanized with zinc were slowly introduced as an alternative to brass.  The steel rivets continued to be manufactured in four parts with a solid metal head.  Despite the switch from brass to steel, many firms continued to supply helmet assembly plants with old stock until depleted.  Examination of original rivets clearly illustrates that at least three of the firms manufactured brass rivets through 1939.  At least one firm continued to make brass rivets through 1940.  Many helmets dated 1941 and later exhibit hollow headed rivets.  In general, hollow headed rivets were as durable as their steel counterparts.