We offer a 60 day warranty with a guarantee of a full refund in case the product fails or does not fit your pop-up stoppers. This warranty is inclusive in the perks already and you don't have to buy it separately.
Yes, you could still use a TubRing with something heavy to put on top of it. For example, you could use a piece of rock, a steel ball, or anything round or flat but heavy. If you can't find anything like these, you could simply purchase a pop-up drain stopper for less than $10 on amazon or the home depot.
Don't see the answer to your question? Ask the project creator directly.