The NuPac is a precision molded seal that combines a U-Cup with an O-Ring. Under zero and low pressure, the O-Ring pressurizes the lips of the U-Cup allowing it to seal. As system pressure increases, the O-Ring is energized and forces the lips outward, changing its behavior from a squeeze type seal to a traditional lip seal. Dichtomatik NuPacs come in 4 designs: Standard, Deep, Square B, and B-Lip.