The Fish-On!A(R) Cup Holder is the perfect accessory. Its unique design features a gyroscope motion that will keep your drink contained no matter what weather you may find yourself in. The rod mount cup holder will fit into any Fish-On!A(R) Side Mount (not included) and can be mounted to any flat vertical surface or to a 7/8" or 1" rail with the optional Rail Mount Adapter. Gyroscope motion Will fit into any Fish-On! Side Mount (not included) Can be mounted to any flat vertical surface or to a 7/8" or 1" rail with the optional Rail Mount Adapter Dimensions: 8"H x 3.75"W x 3.75"D