6.0 oz. Synergy fabric powered by Nomex IIIA fiber provides inherent heat and flame resistance. No melt, no drip, no burn. Collar can be worn in two ways: as stand-up collar with hook and loop strap to protect your neck from the heat or tucked underneath the folded-down traditional-style collar using hook and loop at back of the neck. Bar-tack reinforcement in all stress areas.