This gimmick was invented by Bob Ostin and marketed by Davenports as “Bob Ostin's Dice Prediction,” 1953. An ad appeared in Abracadabra, Vol. 16 No. 408, 21. Nov. 1953, back cover. Tony Corinda also mentions Ostin's clip in Thirteen Steps to Mentalism, 1958, p. 186. Ostin's clip was made with a rubber band or elastic. The model with a metal spring was developed and marketed in 1959 by Robert Nelson (sharing credit with Syd Bergson) under the name “Nelson's Mental-Gimic; see The Linking Ring, Vol. 38 No. 12, Feb. 1959, p. 11.