BACK TO INDEX PRODUCT SUPPORT CONTACT US WHAT’S NEW The Catvent ® is a complete vent cap assembly incorporating a Microcat® catalyst and includes a precision pressure relief valve, flame arresting disk and built in Microcat Custom designs are possible. We can design a vent especially for your battery. Two standard versions currently available including 35mm standard DIN push fit with o-ring seal. See the Microcat® catalyst section for more information about the catalyst in operation.