These fittings are used to be able to add extra breathers to performance engines etc. VW's have a breather system which is fine for standard engines but once you increase the capacity etc often you need the engine to be able to breathe more to relieve the extra crankcase pressure. The easiest place to add extra breathers are to the rocker covers. These fittings allow you to do that. Rocker covers require drilling, The fittings are supplied with rubber seals and lock nuts. For 1/2 inch hose or (12 or 13mm) We also sell 12mm braided hose in the wolfsburg Restos ebay shop.
eBay