Bigger size thermostat housing really helps to avoid cavitation problems. A must have for tracked engines running without thermostat specially in summer or hot weather. It does help too fitted with std oem thermostat. We’ve few different operating range of oem thermostat in stock to accommodate for a specific use. Pleas ask about thermostat. The kit contains 1x2pk housing, 2xbolts, 1 x housing washer.