Surgical scalpels consist of two parts, a blade and a handle. The handles are reusable, with the blades being replaceable. In medical applications, each blade is only used once (even if just for a single, small cut).

The handle is also known as a B.P. handle, named after Charles Russell Bard and Morgan Parker, founders of the Bard-Parker Company. Morgan Parker patented the revolutionary 2-piece scalpel design in 1915 and Bard-Parker developed a method of cold sterilization that would not dull the blades, as did the heat-based method that was previously used.

Medical scalpel handles come in two basic types. The first is a flat handle used in the no3 and no4 handles. The no7 handle is more like a long writing pen, rounded at the front and flat at the back. A no4 handle is larger than a no3. Blades are manufactured with a corresponding fitment size so that they fit on only one size handle. The following table of blades is incomplete and some blades listed may work with handles not specified here.