The three XL current probes add both convenience and expanded current measurement capability. The XL probes are designed to operate with the AM503B and AM5030 Current Probe Amplifiers. They are incompatible with the older AM503 and AM503A amplifiers. The XL (for extra long) probes have eight-meter cables, which allow you to reach test points on large devices such as heavy duty motors or automobiles. In addition, connecting to test points on transportation platforms such as trains, ships, or aircraft is much easier with the XL probes.