Accommodates surface mounted applications and provides an additional 50 mm depth to the Thermostat Protector STI-9110. Has conduit knockouts on the bottom and top with filler pieces to fill conduit cut outs when no exposed conduit to mount over. When used outdoors, this spacer (with a conduit gasket) will accommodate 40 mm conduit. For indoor applications, where no conduit gasket is required, this spacer will accommodate 40mm and 85mm conduit.