The No.21 is a large version of the No.10 blade with a curved cutting edge and a flat, unsharpened back edge. Larger than the No.20 but smaller than the No.22 the No.21 fits handles 4, 4L, 4 Graduated & 6B.
20 Packets of 5 blades per box = 100 blades
Non Sterile, Carbon Steel. V.P.I. Protected. Size 21