Shell
From the early 1900s until about the 1940s, the shell of the football helmet was made of leather, but technology has greatly advanced how the shells are made. The outer layer of the helmet is now made of plastic, typically a type of polycarbonate that flexes to absorb and deflect impact. The outer shell of the helmet protects the top, sides and back of the head, as well as the cheekbones, and also has vents to allow air to circulate into the helmet, which helps keep players cool.
Padding
Inside the helmet, between the player's head and the shell, sits a layer of polyurethane foam that acts as a cushion to soften blows to the head. One of the newer technologies is the use of thermoplastic padding in the helmets, which have a small hole that allows the pads to deflate when contact is made, and then re-inflate in an instant. According to "Wired" magazine, this new airbag-like technology dissipates more impact than traditional polyurethane foam.
Face Mask
The face mask is affixed to the front of the helmet, allowing the player to see the field while protecting from impact and helping keep errant extremities from striking the player's face. The bars of the masks come in a variety of designs, but most are made from carbon steel with a plastic coating. Face masks can range from lightweight varieties for kickers and skill position players to full cage masks for linemen. Some players attach visors to their face masks for added protection.
Chin Strap
Many football helmets include chin and jaw protection, but all have metal snaps where you can affix a chin strap. Some helmets come with chin straps, and with others you may have to purchase the chin strap separately. Older chin straps are simply made of plastic to help keep the helmet securely on the head, while newer technology features padding made from the same material as the padding and shell of the helmets to help protect the chin during play.
