Garmin Livescope sonar transducer holder for pole mounts. It makes it possible to switch between Forward view, down view and perspective mode. The holder can be attached to a 28mm rod. (I built my rod from an anodized aluminum pool cleaning rod).
Also included is the knob design for tightening and adjusting the angle. Uses 2.5" 1/4-20 pan head bolt and nylock nut.