Carton staplers are used to apply carton staples to boxes and packaging, securing the sides, base, and top for transport. The staple goes through the box flaps and curls back underneath the flap to pinch close. These staplers are used to seal heavy boxes and lightweight packaging like mailers, trays, and single-wall boxes. Battery-operated carton staplers cause less strain than manual-operated staplers. Manual and pneumatic foot-operated staplers are for high-volume applications. Pneumatic handheld staplers use button-operated air pressure to seal staples.