Four medical devices stocks are moving up in their overall rating this week, according to the Portfolio Grader database. Every one of these is graded an “A” (“strong buy”) or “B” overall (“buy”).

Winner Medical Group (WWIN) is progressing from last week’s rating of B (“buy”) as the company improves to an A (“strong buy”) this week. 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.

This week, Antares Pharma, Inc. (ATRS) is showing significant improvement as the company’s rating hops from a C (“hold”) to a B (“buy”). 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.

Medtronic, Inc. (MDT) is seeing ratings go up from a C last week to a B this week. Medtronic develops therapeutic and diagnostic medical products. For more information, get Portfolio Grader’s complete analysis of MDT stock.

Neovasc Inc. (NVCN) shows solid improvement this week. The company’s rating rises from a B to an A. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of NVCN 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.