1-2. Location and Description of Major Components.
a. Helmet Shell (Figure 1-2). Finished with rubber edge beading, the lightweight composite helmet shell (1) protects
the head from Impact. Chafing pads (2) prevent the earcups from chafing against the shell. Cross straps (3) regulate
earcup tension, thereby controlling earseal compression for optimum fit and noise reduction.
b. Liner System (Figure 1-2). The SPH-4B liner system replaces the sling suspension systems of earlier SPH models.
It consists of two liners: an energy-absorbing liner and a thermoplastic liner.
(1) Energy Absorbing Liner. The polystyrene energy-absorbing liner (5) absorbs and reduces impact forces. It is
attached to the inside surface of the helmet shell with hook-and-pile fasteners.
(2) Thermoplastic Liner. The liner (4) is a lightweight comfort liner. It consists of layers of molded plastic attached
to a removable, washable cloth cover. The sides of the cloth cover are made of pile fastener to attach the liner to hook
fastener on the inside surface of the energy-absorbing liner. The preformed liner fits most head shapes.
Figure 1-2. SPH-4B Helmet Shell and Liner System