? INSTALL WITH OR WITHOUT A BALLAST. These Parmida tubes can be installed with a ballast (plug and play) or without a ballast (direct installation). 18W without ballast, 20W with a ballast. Please check Ballast compatibility before purchase. Standard international 4' T8 tube shape. ? SINGLE OR DOUBLE-ENDED CONNECTION. This tube is UL-Listed for installation with a single-ended or double-ended connection. Fast, simple and secure installation under the functionality of your choice, this Parmida tube is designed with user experience as the defining motivator. ? KEEP ORIGINAL TOMBSTONES. This tube installs directly into your fixture’s original shunted sockets (tombstones). You will not need to retrofit your fixture with non-shunted sockets. ? FULLY CERTIFIED: UL-LISTED & DLC-CERTIFIED. 5 YEAR UNLIMITED WARRANTY. This product meets strict requirements to be considered energy efficient, safe and reliable. Eligible for state and nationwide rebate programs. ? SHATTERPROOF. These T8’s are designed with a frosted shatterproof film protected glass housing which allows for safe installation in fixtures, with or without wire guards.