Shame on me for not paying closer attention to the dimensions of the square coasters, but they must literally be made for an old school tea cup. They will not work for coffee mugs or stemless wine glasses. I use a lot of bamboo products in my home, and the quality of this product is fine. So if you need tiny coasters, they'll be great. While I appreciate the reasons for Bamboo Switch's no return or refund policy, I am now stuck with coasters that I cannot use. I will put them out on our next curb alert to give away.