The beauty of buying sax pads with only a center hole and then installing the resonator of your choice is the flexibility and economy that this approach offers.
You can accommodate special requests of customers and properly service a variety of brands without having to stock many different pads. It’s an additional benefit to have the predictable results of using one pad that you know and trust.
Ideally, you want to compare the resonator to the tone hole it is intended for. However, matching it to the pad size alone can get you close.