If you own a high power audi I5 you probably at some point or another have had issues with large amounts of liquid oil 'sloshing' out of the stock vent port on the side of the block. Frankly, the way audi designed this is much more of a 'blow hole' than a crankcase breather.
To help address this issue, INA Engineering has come up with a nicely engineered 2 piece cranckcase breather 'puck' that replaces the factory tin breather port with provisions for packing with stainless wool to both allow large volumes of air, but critically low volumes of OIL from escaping. sold without fittings. can be setup for AN flare or a barb fitting depending on how you want to setup the rest of your PCV system.