Double-braced tripod base Fulcrum shaft height adjustment With Memory Lock for height adjustment For thrones of the Gibraltar 9608 model series Also suitable for other seats with 7/8" (2.22 cm) tube mount Single braced tripod base Fulcrum shaft height adjustment With Memory Lock for height adjustment Fits seats with 7/8" (2,22 cm) tube mount Height adjustable approx. 51 - 71 cm