OMEGA Thermowells are available in a variety of materials such as Brass (ASTM B-16), Carbon Steel (C-1018), Stainless OMEGA Thermowells are available in a variety of materials such as Brass (ASTM B-16), Carbon Steel (C-1018), Stainless Steel A.I.S.I. 304 & A.I.S.I. 316, Monel. Wells are also available in specialty materials.