Kamizelka kuloodporna and other 84,100 icons from Icons8 icon pack follow the visual guidelines of the operating systems: Windows, iOS, Android KitKat, and Material. PNG format is free up to 100x100 px. Icons are availble for download in PNG and vector (SVG, PDF, EPS, and more).
It is like a shirt, but sleeveless. There is a big square in the middle that is presumably for the armor part of the vest, and it takes up much of the "stomach" area. Both sides have two sets of small squares that are aligned on top of one another on either side of the vest.