Aquascape®️ 48026 Dual Union Check Valve 2.0. The Aquascape Dual Union Check Valve 2.0 effectively prevents backflow in ponds and water features while providing a professional pump and plumbing connection inside pond skimmers and Pondless® Waterfall Vaults. The heavy-duty, swing-style check valve flapper is built to last and maximizes water flow through the valve when open while preventing the backflow of water when the pump is shut off or during a power outage. A set of innovative reversible fittings takes the guesswork out of finding the right pump or filter fitting; simply rotate the fitting to the desired orientation for your application. Union connections on both sides of the valve make pump and filter maintenance quick and easy without the use of tools. The Dual Union Check Valve 2.0 is compatible with a wide variety of filter sizes, making it easy to extend the valve height when needed.