What are lax pinnies?

Lax pinnies are practice jerseys for the game of lacrosse. Lax is a commonly used nickname for lacrosse and a pinny is a mesh tank top used for any number of sports, primarily when dividing athletes into groups.

Pinnies are usually sleeveless and made of lightweight mesh so that they can be worn over other sports apparel without adding bulk that would restrict movement or cause an athlete to overheat during vigorous drills or competition. They are often reversible, which means they have different colors or designs on the inside and the outside, so players can be divided easily into two distinct teams in order to scrimmage.