Pack of 5 Bahco 3940-150-18-HST Heavy Metal Reciprocating Blades 150mm 18 TPI Bahco 3940 Series Metal Reciprocating Blades are made from virtually unbreakable, bi-metal Sandflex(r). Shaped for fast and aggressive straight cuts but still flexible for narrow cutting. With a slope-shaped nose for various types of cuts in more demanding applications. Heavy Standard (HST) blades have precision ground teeth. The wider body makes it more rigid and has a higher resistance to fracturing and bending, allowing straighter cuts. Standard (ST) blades have coarse precision ground teeth are a series of flexible blades. The standard body makes it more flexible and easier to bend into position. Bahco A06 B2070