The G-Force 360 helmet support is constructed of high density, fire retardant foam. The outer layer covering is soft, knit CoolTec and is removable for easy cleaning. SFI 3.3 rating. Measurements: small: up to 12.5 inch; medium: 12.5 inch - 15.5 inch; large: 15.5 inch - 19.5 inch. Available in black, blue and red.