This week, four medical devices stocks are improving their overall ratings on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

This week, Winner Medical Group (WWIN) is making solid headway. The company’s rating improves to an A (“strong buy”) from last week’s B (“buy”) rating. Winner Medical Group engages in the research, development, manufacture, and marketing of cotton-base medical dressings and medical disposables. For more information, get Portfolio Grader’s complete analysis of WWIN stock.

Antares Pharma, Inc. (ATRS) is making progress this week as its rating of C (“hold”) from last week increases to a B (“buy”) rating this week. Antares Pharma develops pharmaceutical delivery systems, including needle-free and mini-needle injector systems and transdermal gel technologies. For more information, get Portfolio Grader’s complete analysis of ATRS stock.

Neovasc Inc.’s (NVCN) ratings are looking better this week, moving up to an A from last week’s B. For more information, get Portfolio Grader’s complete analysis of NVCN stock.

Medtronic, Inc. (MDT) earns a B this week, jumping up from last week’s grade of C. Medtronic develops therapeutic and diagnostic medical products. Shares of the stock have been trading at an exceptionally rapid pace, up twofold from the week prior. For more information, get Portfolio Grader’s complete analysis of MDT stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.