Flak Jacket

Flak jackets are a form of protective clothing designed to provide protection from such things as blunt-force trauma or even bladed weapons, shrapnel and other projectiles or weaponry. They are usually worn by chūnin and jōnin over their normal clothing in most villages, although the design varies among the villages and have also changed over time. 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 Hatake's case when he normally does this secretly to extract a kunai.

Trivia

 * In episode 190 of Naruto: Shippūden, Iwagakure genin are seen wearing flak jackets.