AEMC 2118.85 Kelvin Probes Pistol Grip 20 ft 25 A, Spring Loaded. The AEMC 2118.85 Spring-Loaded 25A Kelvin Probe can measure low resistances very accurately using micro-ohmmeters with .157 to .236 inch (4 to 6 mm) diameter binding posts or .157 inch (4 mm) diameter safety terminals. The AEMC 2118.85 ensures good contact at the measurement point even if the surface is uneven. This unit also has very low resistance. Measurements are made in 4-wire mode, so lead resistance compensation is not necessary.