Trefethen Estate winery is one of the few in Napa Valley that's never bought any grapes. All of their wines are produced with grapes sourced from their estate vineyards, mostly the 61 vineyard blocks that make up their Main Ranch. The establishment of the Oak Knoll District AVA in 2004 is in large part due to Trefethen's presence there. Just south of Yountville and Stag's Leap, Oak Knoll is one of the coolest regions in the Valley. The Cabernet ripens slowly over an extended season developing complex flavors. This 2014 is 86% Cabernet Sauvignon, 6% Malbec, 6% Petit Verdot and 2% Merlot, all from the Main Ranch Estate vineyard and was aged 18 months in 59% French, 31% American, 10% Hungarian oak barrels. This was awarded Gold Medals in the Critics Challenge Wine Competition and the San Diego International Wine Competition. James Suckling scored it 92 points saying "A firm and silky wine with plum and light fresh herb character. Medium body and juicy fruit. A classy and traditional Napa cab. Delicious now or hold for later."