Splines and Points
The metal stem at the top of cartridges has ridges called splines. The ridges fit into the corresponding grooves within a handle. The splines are measured in points. Each ridge or spline is one point. For example, a 16-point cartridge has 16 splines (ridges).
COUNTING SPLINES A quick way to count the number of splines (ridges) is to count half of the ridges and multiply times two. Or count one fourth of the ridges and multiply by four.