The V4 Vortex Gearcase Adapter Ring - 3-Blade (991216) is a circular accessory with the unique feature of having threads with two different diameters on both sides of the filter. It is for vortex propellers. It is suitable for 20-30 HP applications. Prop pushes it up against forwarding gear and receives the load from the boat propeller. This prevents the propeller from moving too far back or too far forward. Key Features: Superior lower unit filler adapter 100% brand new and original engine parts manufactured with the highest quality materials available in the industry with zero fault production. It is easier to replace the gear oil in your outboard motor's lower unit. Built to last Compact, simple to transport, and install. Designed to provide maximum comfort and convenience Proven and tested for dependability throughout the manufacturing process to ensure it meets our quality standards Marine-grade approved product Specifications: SKU: 991216 UPC: 014984012720 Weight: 1.00 LBS Manufacturer Part Number (MPN): 991216