I’ve shipped millions of wax rings. Most importers overcomplicate this. There are only 3 things that matter.
Wax quality. Cheap wax has more petroleum byproducts, smells stronger, gets brittle faster. Good wax is smooth like butter. You can feel the difference.
Reinforced or not? A standard ring is just wax. Reinforced has a polyethylene sleeve inside. For a few cents more, you get way more margin for error. I tell importers: stock reinforced. Your return rate drops.
Size. Standard is 3-inch. Jumbo is 4-inch. Make sure your label says which. The number of Amazon returns from wrong-size orders is staggering.
That’s it. Good wax, reinforced sleeve, clear sizing. Ask for ROHS and REACH certs. If your supplier hesitates, find a new one.