The UTG RBUAM01 Pro AR15 30 Round Polymer Magazine - 5.56 is designed to feed and function flawlessly. UTG is known for its quality products and this 30 round .223/5.56 magazine is no exception. This magazine has endured multiple tests that include temperatures ranging from extreme heat to extreme cold, water, dirt, dust, drop and even a weight test. Yes, a weight test, drive your truck over it, pick it up and place it back in your rifle to continue shooting.