Tacks are sold as one-ounce, two-ounce, and so on according to size.

Do not use tacks for fastening wood to wood, but only for fastening leather or cloth or the like to wood. The pointed wedge-shape of the tack tends to split thin wood, and is not at all suitable to fasten two pieces of wood together, particularly in thin wood or near the edge. Possibly you may have seen some disastrous results from the attempt to tack pieces of wood together.