Questions

On page 258, Mr. Pip and Herbert are talking with Mr. Wopsle, and his friend Mr. Waldengarver, and the owner, at the theater. The owner of the theater tells Mr. Waldengarver," The last Hamlet as I dressedmade the same mistakes in his reading at rehersal, till I got him to put a large, red wafer on each one of his shins." I am wondering what would be the equivalent of a wafer, that he is refering to, in the present day?