This is a Signin 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 13,000 icons, all in the same style and quality.
This is an image of a circle. The circle has a small blank area at the top of it. Inside the circle is a downward facing arrow that begins at the blank area of the circle and ends just past the center of the circle.