The BeA AT-A18 air powered carton closing stapler clinches A series 1-3/8" crown staples from 5/8" to 3/4 in length. One year warranty. This durable carton stapler is designed to staple corrugated cardboard for closing boxes. Carton closing staplers in the AT-A series have separate adjustments for staple leg length, depth of penetration, and tightness of clinch. This allows for through and blind clinching of box flaps.