Foil wrapped carbon steel gamma sterilized -- Blades are packed 100 in a box, and cases contain 10 boxes. The difference between the composition of carbon steel and stainless steel is that carbon steel is an alloy of about 99.5% iron, 5% carbon - so almost pure iron, but stainless steel is about 2 parts iron for 1 part chromium. Carbon steel is generally harder and stronger but less corrosion-resistant. ($133.00/case sold separately).
This size fits #4 handle. Other sizes for #4 handle are 20, 22, 23, 24 and 25