This is a Full Version Filled 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 12,800 icons, all in the same style and quality.
There is a rectangle with an arrow pointing down into the center from the top. The base of the arrow is not filled in, the outline is one continuous line, with no breaks. Under the rectangle is the word FULL in all capital letters.