The terminal blocks, fit all Pyromation series 31, 34, 49, 63, 91 and 800 series connection heads. The terminal blocks are provided with a steatite ceramic base, brass terminal pieces, and stainless steel screws. These terminal blocks are not rated for high voltage use, but can be used in temperature sensor or low voltage Class 2 circuits. Series 341 terminal blocks accept up to an #8 gauge wire.