BeaverCraft SK4S2 – Open Curve Hook Knife X 2. The wonderful SK4S (right-to-left cutting action) and SK4LS (left-to-right cutting action) hook knives. The blades are 60mm long, making the total tool lengths at 260mm long. These delicious knives with their open curved blades are wonderful for carving those more shallow spoons. Razor sharp blades protected by their nifty leather sheaths.