This icon is simply the letter "O" centered inside a square shape. The square shape enclosing the "O" has rounded corners. The width of the letter is approximately one third the width of the square.
This is a Oxygen icon. We've made it in iOS style
, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 13,700 icons, all in the same style and quality.