Thybar Corp. has released Vibro-Curb, which has integral, vibration-dampening spring isolators. The curbs provide mounting for rooftop HVAC units and come with a 2-by-4-inch wood nailer for attaching roofing felt. The curbs also have a flexible, 9-inch counterflashing that provides a weather seal. Company officials say the curbs offer a minimum of 90 percent isolation efficiency with the isolators. The curbs are custom-sized and spaced to accommodate the rooftop unit’s weight and center of gravity for optimum vibration dampening.