"Mount your fishfinder confidently with the RAM Mounts Ball Mount with Round Base for Humminbird Helix 5 & Helix 5 G2 Units. Featuring a round 2.5""-dia. base in Universal AMPs Hole Pattern, a double-socket arm, and a 3""L x 1.5""W rectangular base, the Ram Mounts Ball Mount with Round Base fits Humminbird Helix 5 & Helix 5 G2 units easily and several other fishfinders, or other objects you want to fasten securely. Rectangular base has 4 holes with a center-to-center pattern of 2.5""L x 1""W. For most applications, it supports up to 10 lbs. Overall Height: 7.35"". Mounts Humminbird Helix 5 and Helix 5 G2 fishfinders Round 3.5""-dia. base, double-socket arm 4 holes in rectangular base Holds any light square or rectangular object Supports up to 10 lbs. View the RAM Mounts Kayak and Boat Compatibility Chart."