Coasters are made of ceramic with a cork backing.
Each coaster is about 4" in diameter and 1/4" thick.
I offer discounted shipping if you buy multiple items from me at the same time. To get the discount, add all of the items you are buying from me to your cart, then at checkout instead of paying right away, select "request total from the seller". I will then send you an invoice for the total of all items including a discount on the shipping.