These filters fit most Dynasty Spas hot tubs as well as many others. This is for 4 filter so you have 2 sets of 2 so that you can rotate them.
They are the same size as filter PDC6000-AFS, 6CH-940. These are microban upgraded so they have the blue filter media just like in the picture, they are not the white filter media that has no anti-microbial protection.
