The RAM Round Base with 1.0 Inch Ball consists of a 1" diameter rubber ball connected to a flat 2.5" diameter base. This mount has pre-drilled holes, including the universal AMPS hole pattern.
I used this to mount a Garmin Echo 100 and the bolts match perfectly. Combined with a ram arm and Yakattack ball on Geartrac and its a great mounting option that is easy to remove for a clean kayak and nothing in the way.
if you plan on mounting anything to anything, RAM mounts are the best.