Our stone coasters will absorb moisture and is heat resistant. A thin cork layer on bottom protects surfaces. 4.25" stone coasters - set of 4 - Made in USA CARE: Rinse spills to prevent staining. Stains: one part bleach to three parts water. Soak overnight. Rinse thoroughly and allow to air dry cork side up. Red wine and similar stains will prove difficult to treat on any light colored areas of absorbent stone. Not recommended for use with metal containers as these can scratch the surface.