1/4" NPT Oil Return Check Valve with 1/2" Hose Barb

An Oil Drain Check Valve is required for ALL Airsep installations.

The CD246 oil drain check valve included in AirSep kits does not have a hose barb attached to the lower end.
This MD105 unit does have a 1/2" hose barb at the lower end, and is offered as a convenience so you don't have to source and attach the barb yourself. (The bottom thread size on the valve is 1/4" NPT.)

Be sure to install oil return check valves in as near a vertical position as possible - and never more than 45° from vertical. Walker recommends positioning the check valve at, or just above, the oil pan rail on the engine. When the engine is running the oil level should not be above the pan rail so you are assured that the oil will drain while the engine is running.

Oil return check valves are typically installed in an auxiliary dip stick port or other opening into the engine block. Another option is to weld a 1/4" NPT fitting onto the existing dip stick tube.
Installers must verify that the port they are returning the oil through is not part of the pressure galley, or the check valve will not open when the engine is running.

How much oil flow are we talking about? Typically just several ounces per hour.