Optimum is pleased to announce the arrival of another CNG tank certification! The 21-inch diameter and 60-inch overall-length (21X60) Type 3 CNG tank was qualified to NGV2-2007 and DOT FMVSS304. This is a 3,600 psi service pressure cylinder with a 20-year service life and 21.0 gge. A third party inspector performed or witnessed all testing. The tank design exceeded all test requirements. The CNG tank is available for immediate sale.