It's a logo of Rocket Boot reduced to a boot with a small rocket attached to it. It looks like an ordinary boot but it has a small rocket the shape of a flashlight on the back of the boot. This boots are designed to give humans flight.
This is a Rocket Boot 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 13,300 icons, all in the same style and quality.