French
French size describes the nominal outer diameter of many catheters, sheaths, drains, and lines. One French corresponds to approximately 0.33 millimeters.
Gauge
Gauge commonly describes needle diameter. Unlike French size, a larger gauge number indicates a smaller needle.
Wire diameter
0.014-, 0.018-, and 0.035-inch platforms are not interchangeable. The wire must match the device lumen and the support the procedure requires.
Length and working length
Confirm whether the stated length refers to the whole device, the usable shaft, or a functional segment such as a balloon or covered portion.