Murphy 20BTG-300-5-D1209.
Oil Temperature Gauge. 140-300°F (60-149°C). 2" heavy duty plated steel gauge with sensing bulb. High quality diaphragm-actuated gauge. As temperature rises, the fluid in the sensing bulb vaporizes to apply pressure on the diaphragm; the movement translates this vapor pressure to a calibrated reading of temperature on the dial. Black face with white pointer, green, yellow and red scale. Polycarbonate, high-impact lens. Bezel is polished stainless steel. Mounting hole diameter 2 1/32" (52mm). 2 9/32" (58mm) depth including temperature capillary. Maximum panel thickness: 1/4" (6mm). Sensing bulb attached to 59" cable with 5/8-18NF union nut on bulb end with 21mm adapter. Includes mounting bracket hardware and installation instructions.
Spec sheet available in PDF format.