Avery White Shipping Labels for Laser Printers with TrueBlock Technology 3 1/3 Inch x 4 Inch, Box of 600 (5164) TrueBlock Technology completely covers everything underneath Labels are bright white for professional results every time Jam-free and smudge-free printing is guaranteed Smooth-feed sheet edges prevent buildup that causes printer jams Customize with free tools, software and templates from avery's Website