Front swept Super Sealer knife with Chrome insert for longer wear and 1/2" O.D. open ended tube. This knife is often referred to as a Mole style knife.Provides superior sealing action in a wide variety of soil types and conditions. The wider foot, running at a slight upward angle, breaks up an area of the soil just below the surface. This causes the NH3 to attach to soil particles more rapidly and the gas will resist the natural tendency to move upward. Pack of 1