The Stiper knives are made from D2 Steel well known for being difficult to work with but very strong.
D2 Steel Analysis:
1.5 - 1.6%
Carbon
0.2% - 0.6%
Silicon
0.15% - 0.45%
Manganese
0.03 (max)
Phosphorus
0.03 (max)
Sulphur
11%
Chrome
0.7%
Moly
0.8% - 1.1%
Vanadium