Allergy Be Gone is advertising the 50250N. WARNING: THEY NO LONGER CARRY THEM.IF YOU ORDER ONE, YOU'LL GET THE 50251 (WHICH DOESN'T HAVE A WASHABLE FILTER). THEN YOU WILL HAVE TO DEAL WITH THEIR BAD RETURN POLICY. Currently, they can't "find" the package that I returned to them and aren't crediting my return until they can find it.