Load full strip of (100) ARROW staples of .030 wire in sizes 1/4 in , 5/16 in and 3/8 in staples. Visual refill window. Perfect for screen repairing, light upholstery work, kitchen shelf trimming, closet lining, cornice covering and scores of other light duty household tacking chores. No. JT21M : All steel construction. Jam-proof mechanism. Hand-contoured handle. Built-in staple lifter. Household baked enamel finish. No. JT21CM: Durable hi-impact molded plastic housing. Safety handle lock. All steel channel andtrack for non-wearing, jam-proof performance.