Or peeling debris. The difference. On a lam, the weight will be lost when it peels. On a struck through debris, the weight can be increase. On a lam, they tend to run in a straight line as it was something rolled into the stock metal. On a struck through debris, they are not flowing in a straight line. Can end up partially on the rim or even the edge of the coin. Kind pf fans out at the edge of the debris.