18" standard capacity black stainless steel Tranquil Whistle-Free gas flex line only. To eliminate the nuisance whistling found on those tough installs. 1/2" OD - 3/8" ID, equipped with 1/2" female pipe threads on one end and 3/8" male pipe threads on the other end. Polymer coated and will resist blistering in the heat of the fireplace. Shipping is free, however we ship only within the continental United States.