Weights

A is a heavy object used for training by weighing down the user. Rock Lee wears a pair of ankle weights with the word written on them. During the Chūnin Exams, he asks Might Guy to remove them while facing Gaara, his speed increasing after their removal. The weights are heavy enough to leave a small crater on the floor.

Other appearances
In the first three games from the Naruto: Ultimate Ninja series, Rock Lee's weight appeared as an item that can be thrown on opponents to temporarily reduce their speed. It is named in the first and second game and Weight of Determination in later releases. In the fourth game onward it was replaced by a tag with the same effect, the weight having minor or no appearances afterwards.

In Naruto the Movie: Guardians of the Crescent Moon Kingdom, Rock Lee wears heavy bars on his ankles. Besides their training purpose, those bars can also be combined into weapons like a pair of nunchakus, a bō staff, and a long chain. Rock Lee used them on his fight against Kongō.