Flex cable saver. This can be used to prevent the flex cable from coming loose from your boat if the coupler comes loose. Made of CNC-cut aluminum for lightweight. Less than 2 grams! Anodized in silver with a 3mm grub screw. Options: .150" (3.8mm) Cable 3/16" (.187", 4.75mm) Cable Install note: Install this item as close to the coupler as possible. In our picture, we spaced it for display purposes only, so it was easy to see. Do not over-tighten. Note: The flex cable and coupler in the picture are for demonstration purposes only and are not included. .187 Saver fits the following boats: Proboat Zelos, ProBoat Geico 36, ProBoat Voracity< Sonic Wake 36, and TFL Zonda. Specs: Outer diameter: 12.5mm Width: 5.5mm Requires: 2.0 mm Allen driver.