The pressure gauge measures copper,copper alloy corrosivesless gas,liquid etc media pressure .spot compressioned direct Pressures:: 0-100-300....15,000 psiFlanges:: Front, back, & U-ClampSizes:: 1.5, 2, 2,5, 4, & 6 inchCases:: SST, ABS, Chrome, etcConnections:: Center Back with flangeor filled or dry but fillable flange pressure gauge