This icon is a part of a collection of Ctrl flat icons produced by Icons8. Icons follow the guidelines of iOS, Windows, and Android and are designed by a single designer, guaranteeing the consistent quality. Both PNG and vector are available.
This icon for control is a rectangle with sides that are nearly equal in length. The width is a bit larger than the height. The corners are rounded, and at its center are there letters ctrl, with the C being capitalized.