Each business day, TheStreet.com Ratings compiles a list of the top five stocks in five categories -- fast-growth, all-around value, large-cap, mid-cap and small-cap -- and publishes these lists in the Ratings section of our Web site. This list is based on data from the close of the previous trading session. Today we focus on mid-caps. These are stocks of companies that have market capitalizations of between $500 million and $10 billion that rank near the top of all stocks rated by our proprietary quantitative model, which looks at more than 60 factors. The stocks must also be followed by at least one financial analyst who posts estimates on the Institutional Brokers' Estimate System. They are ordered by their potential to appreciate. Note that no provision is made for off-balance-sheet assets such as unrealized appreciation/depreciation of investments, market value of real estate or contingent liabilities that might affect book value. This could be material for some companies with large underfunded pension plans. Circor International ( CIR) has been manufacturing an array of valves since the early 1900s. Valves range in application from generic products for heating and cooling to more specialized steam catapult valves on nuclear-powered aircraft carriers and cryogenic valves used in the space shuttle. Circor has been rated a buy since November 2004. The company's strengths can be seen in multiple areas, such as its impressive record of earnings per share growth, compelling growth in net income, revenue growth and solid stock price performance. Earnings per share grew 68.9% for the first quarter of fiscal year 2008 when compared with the same quarter of fiscal 2007, which brought its three year average EPS growth rate to a solid 47.7%. The company reported 9.5% growth in its revenue over the same period, which trailed its industry average but allowed it to boost net income, which grew 74.1% for the interim. In addition, as of the market's close on May 20th of this year, Circor's share price has jumped 38.8% compared with its closing price of one year prior. The stock currently trades at a valuation level that is in line with its peer average and a discount to the S&P 500 average.