Flak jackets are usually worn by chūnin and jōnin over their normal clothing in most villages, although the design varies among the villages. Although they are called jackets, they look more like a vest, or other similar garments. The jackets are among the most iconic pieces of shinobi equipment. Most of them have pockets, which can be used to store scrolls and also allow a ninja to access them with only one hand, as seen with Kakashi's case when he normally does this secretly to extract a kunai.

Kirigakure flak jackets are slate grey. They come with or without a neck-guard but have elongated padding over the shoulders.