The SMF/VRLA series is accumulator battery designed for hybrid cars the manufacturer installs these batteries on the TOYOTA Prius and others. In the hybrid cars, batteries are normally installed inside of the car - in a trunk room or under a back seat. Therefore, the structure discharging harmful gasses of a battery into outside of the car is required. YUASA SMF/VRLA series batteries can absorb carbon-dioxide gas and discharge it out of the car. The batteries meet all the safety requirements.