Muller's Ratchet. (Book Reviews: Sex and Death in Protozoa. The History of an Obsession.)

A hand mounted chalk eraser has an elongated flexible felt pad and three fastening loops secured to the pad, one loop near each end and one in the middle. One end loop extends about the user's little finger; the other end loop extends about the user's wrist, and the middle loop extends about the palm and back of the user's hand, to hold the eraser securely on the edge of the user's hand remote from his thumb. In another embodiment, the pad is shortened and only the wrist loop and the middle loop and used.