TheStreet.com Ratings provides exclusive stock, ETF and mutual fund recommendations using proprietary tools. Our "safety first" approach aims to reduce risk while achieving total return performance.BOSTON ( TheStreet) -- The following companies have market capitalizations between $50 million and $500 million and "buy"-ratings from our proprietary quantitative model, which considers more than 60 factors. They are ordered by their potential to gain. PetMed Express ( PETS) sells medication and health products for dogs, cats and horses. The numbers: Fiscal first-quarter revenue increased 13% to $77 million. Net income grew 22% to $8.1 million and earnings per share climbed 29% to 36 cents, helped by a lower share count. Its operating margin increased from 14% to 16% and its net margin passed 10%. The company has no debt and a quick ratio of 3.7, which indicates outstanding liquidity. The stock: PetMed is up 3% this year, underperforming the Dow Jones Industrial Average and S&P 500 Index. The stock trades at a fair price-to-earnings ratio of 17 and doesn't pay dividends. Applied Signal Technology ( APSG) provides intelligence, surveillance and reconnaissance solutions for the defense and homeland security markets. The numbers: Fiscal second-quarter revenue increased 18% to $54 million as earnings doubled to $4 million, or 31 cents per share. Its operating margin climbed to 12% and its net margin rose to 8%. The company has an ideal financial position, with just $4 million of debt and $55 million of cash, amounting to a quick ratio of 4.6 and a debt-to-equity ratio just above zero. The stock: Applied Signal Technology has advanced 32% this year, outperforming major U.S. indices. The stock trades at an expensive price-to-earnings ratio of 25 and offers a lackluster 2.1% dividend yield.