The standard probe contains an RTD assembly with an aluminum general purpose (GP) head. A terminal block is mounted on the interior of the GP head. The GP head has 1/2" NPT threads where the probe is mounted and a 1/2" NPT conduit outlet for your wire connections. This RTD assembly is also available with a four inch long stainless steel support tube for use with ceramic sheaths and adjustable mounting fittings. The support tube is an 1/8" larger in diameter than the sheath diameter. When ordering with support tube add the suffix (ST) to the part number. Standard support tube is four inches long and can be made to most any length required.