Masonite bats are the workhorse of the pottery studio and, when properly cared for, will last for years. Very economically priced, they are slightly absorbent for good clay adhesion. Made from wood fibers and tempered with a thin spray of linseed oil, they contain no formaldehyde or other chemicals. 1/4 inch thick for easy storage. Do not saturate masonite bats or submerge in water- this will cause them to warp and delaminate.