The upper spray arm rotates and sprays water to clean the dishes inside the dishwasher tub. If your dishes are not being cleaned properly, you should check if there is an issue with the spray arm. To check your spray arm, make sure the spray arms can move evenly and freely on their bearing rings and mounting brackets. Remove your spray arm and check to ensure they are straight and undamaged. This spray arm is made of high-quality plastic and is just over 5 inches long.