I had a bunch of short pieces of 3/4" unfinished hardwood flooring left over from building my home and they are great for smoking. Clean, bark free, easy to store since they are standard size. A standard common size is 3/4" thick and 2 3/4" wide by whatever length. They fit the smoke box perfectly. Typical species are ash, oak, cherry and others. Any floor installer would probably give you his leftover cutoffs and even if you had to buy it a typical price for the cheaper grades that have some knots is in the $2 a square foot range. One square foot would charge my smoker about 4 to 6 times I suppose, maybe more.