Extra Dovetail Shoe. Mount this dovetail shoe on any 8" or larger SCT, or any flat or curved surface over 3 1/2" in diameter. Multiple holes in the base allow you to mount the base with one or two screws. This base will work with the following Stellarvue ring systems: R50D, R50F, R50S, R80D, R80F or R80S. With this extra base, you can use one finderscope for two telescopes.