Bigblue prides themselves with the latest most innovative designs to better accessorize the professional photographer s setup. They continuously utilize the lightest, strongest, most dependable materials available today. Not one expense was spared in Bigblue s accessory line of threaded adapters. This - 20 thread adapter is comprised of T6061 aluminum, fiberglass resin and stainless steel to give you one of the strongest and toughest thread adapters available today. Each Bigblue - 20 thread adapter is corrosion resistant and is supplied with an O-ring seal for better gripping force.