UPBattery batteries are equipped with a safe low pressure venting system, which operates from 1 psi to 6 psi. The venting system is designed to release excess gas in the event that the gas pressure rises to a level above the normal rate. Afterwards,the venting system automatically re-seals itself when the gas pressure level returns its normal rate.This feature prevents excessive build up of gas in the batteries. This low pressure venting system, coupled with the extraordinarily high recombination efficiency, ensure UPBattery batteries be the safest VRLA batteries available.