X-Acto's #1 Knife has a 4-7/8" long aluminum handle, and comes with a standard #11 blade, and safety cap. It can also take blades #10, #12, #16, and #17. No. 51 - This set includes one #1 Knife with a #11 blade attached, as well as two additional #11 blades, a #10 blade, a #16 bla...