These four metal insert coasters are adapted from designs in Frank Lloyd Wright homes. One is from an art glass window in the Lake Geneva Inn (1912; demolished in 1970) in Lake Geneva, WI. One is from an art glass skylight in the R. W. Evans House (1908) in Chicago, IL. One is from a window in the Warran Hickox House (1900) in Kankakee, IL and the other is from an art glass window in the B. Harley Bradley House (1900) in Kankakee, IL. The coasters are made of porous sandstone and have a protective cork backing. They are approximately 4 1/4" square and 1/4" thick and made in the USA.