These are the X-ACTO Zirconium Nitride Coated Blades For "A" handles FEATURES: Z-Series blades are our sharpest, most durable blades ever. Perfect for hobby, paper crafting, woodworking, or any other application that requires a #11 blade. Use with "A" handles. INCLUDES: Five #11 blades in plastic case SPECS: Case, length: 2-5/8" (73mm) width: 3/4" (19mm) height: 5/16" (8mm) COMMENTS: Z-Series #11 blades fit all #1 X-ACTO knife handles. 10/16/12 phijwa