The Tekmar room temperature unit (RTU) 054 consists of a temperature sensor and an adjustable dial which is used to set the desired indoor temperature. The RTU 054 dial has a temperature range from 40 to 100°f (4 to 38°c). in cases where a restricted temperature range is required, the dial rotation can be limited using limit pins supplied with the RTU. A 10K temperature sensor (E.G. 071, 072 etc.) can be mounted remote from the RTU. This RTU does not work with older Tekmar controls. If the RTU is to be mounted on a 2 inch x 4 inch electrical box, an adaptor plate 007 is available for use. made in United States. Manufactured by Tekmar.