This Otwórz archiwum icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 4,300 icons, all in the same style and quality.
It's a logo of a rectangle with the longer side up as in portrait style. Inside the rectangle are zipper teeth starting from each upper corner and meeting in the middle of the image with a zipper as if something is being unzipped.