The Combat Style Spike Novelty Helmet Gives You that Great Look. The Combat Spike Novelty Helmet Contains the Following: (A)Strap Release Buckle. B) Strap Retention System for a Secure Fit.(C)4 Ply Fiberglass Shell with Hand Lamination. (D)Fully Lined Liner. (E) 3 or 4 Inch Steel Spikes. (G)This is NOT A D.O.T Certified Helmet. German Novelty Helmet: Notes: Helmet Sizes:...Helmet Sizes: (Estimates).... Adult:.. Small Sizes are approximately 6-7/8-7.. Medium Sizes are approximately 7-1/8-7-1/4.. Large Helmet Sizes are approximately: 7-3/8-7-3/4.. Extra Large Sizes are 7-3/4 to 7-7/8..