The helmet would have been a very important piece of armor during the Viking Age. The Gjermundbu style helmets are based on the only Viking Age helmet found in Scandinavia. The Sutton Hoo and Valsgarde helms are pre-Viking Age helms. The Spangen or Norman style helms were very popular during the Viking Age and were certainly worn by Vikings. Helms are offered in several different gauges. For steel, lower gauges are thicker. 16GA or 14GA helms are typically used for reenactment. Real Viking helmets were not horned!