The FN303, which looks and feels like a high-tech rifle, is designed to deliver .68-caliber, fin-stabilized projectiles. Its primary effect is the shock of the projectile, which causes the suspect's lungs to expel, producing an incapacitating effect. The test team found that the FN303 fit a variety of users, including officers who wore tactical vests. The system took about 1 minute to set up and load; however, testers recommend the use of an optional sling assembly for long deployments, due to the muzzle heavy design. Testers also recommend installing an optical sight or a weapon-mounted light. A clear magazine allows users to see what rounds are in the magazine and how many are left. A piston activated by a blast of compressed air stored in a bottle sends the projectile toward the target. The air bottle provides sufficient power for approximately 110 rounds; testers fired 120 rounds. The user should not aim for vulnerable areas such as the head or groin. The testing team recommends that the FN303 be considered a necessary weapon in the law enforcement equipment inventory.