This attachment allows you to connect a beer hose to the faucet side of a shank for the purposes of cleaning more than one beer line at a time.
If you have two faucets next to each other, you can connect them using two of these fittings and a piece of 5/16" I.D. hose that would reach between the two faucets. Cleaning solution would then go up from the bottom of one beer line through to the second shank and down through the second beer line.
Please Note: Image is for instructional use. Hose and second attachment not included.