"Grade aluminum" refers to a type of aluminum that has been classified or evaluated based on its quality or characteristics. It indicates that the aluminum material meets certain standards or specifications for its intended use.
It's made of aircraft grade aluminum alloy so you know it's lightweight and really durable. (geekwrapped.com)
This ring is made of precision aircraft grade aluminum alloy. (geekwrapped.com)
For starters, while the devices look similar to the 7 and 7 Plus, they now feature glass on the front and back, complete with an aerospace - grade aluminum frame. (androidauthority.com)