I consider myself a coaster expert. These coasters are large and fit most glasses. They are rubber and non-slip. The raised textured surface prevents moisture from accumulating on the bottom of glasses. They have a rim which keeps the moisture from slipping when transporting them to the sink. I have used many coasters, but these are by far the best!
I bought these because I like how they look and how they would be able to clean. The coaster is black and they hold big drinks and do not slip easy on the table. I like how all the moister from the drink stays in the coaster and it does not leak or get the table wet. Easy to clean I just throw them in the sink once in awhile and wash them with dish soap and air dry. I definitely recommend these over the cork and wood ones. I find that they hold water and germs and sometimes don't even help the moister rolls off and on the table. This is a nice set and I would recommend this for anyone.
I purchased this set for my daughter's college apartment, then decided to keep it for myself because they are so nice. The caddy they come in world match just about any decor, and the quality of the coasters themselves are very good. The rounded edges keep moisture from spilling over and can easily be dumped into the sink.