For outdoor installation of Bosch tankless water heater model # 2700ES (SKU# s 573.6194 760.8359) in approved climates. The Bosch AQOK outdoor vent kit fits on to the top of the Bosch integra evolution and aquastar tankless water heaters to allow the water heater to be installed outdoors in areas that only experience occasional overnight freezes. The Bosch AQOK outdoor vent kit fits on to the top of the Bosch integra evolution and aquastar tankless water heaters to allow the water heater to be installed outdoors in areas that only experience occasional overnight freezes. The AQOK outdoor vent kit is designed to work with the following Bosch tankless water heaters: integra 500 evolution 500 aquastar 2700es and aquastar 2400es. The AQOK outdoor vent kit does not come with built-in freeze protection as these heaters come equipped with freeze protection