The proven Zacks Rank system focuses on earnings estimates and estimate revisions to find winning stocks. Nevertheless, we know that our readers all have their own perspectives, so we are always looking at the latest trends in value, growth, and momentum to find strong picks.Looking at the history of these trends, perhaps none is more beloved than value investing. This strategy simply looks to identify companies that are being undervalued by the broader market. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.In addition to the Zacks Rank, investors looking for stocks with specific traits can utilize our Style Scores system. Of course, value investors will be most interested in the system's "Value" category. Stocks with "A" grades for Value and high Zacks Ranks are among the best value stocks available at any given moment.One stock to keep an eye on is Quanex Building Products (NX). NX is currently holding a Zacks Rank of #2 (Buy) and a Value grade of A. The stock holds a P/E ratio of 17.30, while its industry has an average P/E of 20.54. Over the past year, NX's Forward P/E has been as high as 23.21 and as low as 8.08, with a median of 16.45.Value investors also frequently use the P/S ratio. This metric is found by dividing a stock's price with the company's revenue. This is a prefered metric because revenue can't really be manipulated, so sales are often a truer performance indicator. NX has a P/S ratio of 0.95. This compares to its industry's average P/S of 1.97.Finally, our model also underscores that NX has a P/CF ratio of 9.39. This data point considers a firm's operating cash flow and is frequently used to find companies that are undervalued when considering their solid cash outlook. NX's current P/CF looks attractive when compared to its industry's average P/CF of 16.63. Over the past year, NX's P/CF has been as high as 10.12 and as low as 3.03, with a median of 5.33.These are only a few of the key metrics included in Quanex Building Products's strong Value grade, but they help show that the stock is likely undervalued right now. When factoring in the strength of its earnings outlook, NX looks like an impressive value stock at the moment.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Quanex Building Products Corporation (NX): Free Stock Analysis Report To read this article on Zacks.com click here.