Flex cable saver for .150 or .187 diameter cable. This can be used to stop the flex cable from coming out of your boat if the coupler comes loose. Made of cnc cut aluminum for light weight. Less than 2 grams! Anodized in silver with a 3mm grub screw.Measures: 12.5mm OD, 5.5mm wide. Requires: 2.0 mm allen driver. 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: Flex cable and coupler in picture for demonstration purpose, not included..187 Saver fits the following boats, Proboat Zelos, ProBoat Geico 36, ProBoat Voracity and TFL Zonda.