The Guz's advice as usual is excellent, but I've had better experience with the clay towel. I've kept mine for over 2 years sitting on my big Red Sponge in a bowl of ONR and have found it works smoothly on paint/glass using Wax as the lube. And my clay towel has held up, but know that some have had cracking issues and OPT is looking at new manufacturers. I do prefer the clay towel (whoever the supplier) to bars, erasers, etc, because I feel I have more control and it mars less. I love Hyper Seal as a drying aid on a Pro Coated car and one with no coating.