Mitutoyo 500-197-30 AOS Absolute Digimatic Caliper is the best value in digital calipers. It has a measuring range of 0-8" with .0005" resolution. Equipped with theexclusive AOS sensor technology which is a patented Advanced Onsite Sensor thatoffers improved measurement dependability by increasing resistance to harsh workshop conditions. This caliper features the electromagnetic inductive (AOS) sensorproviding improved resistance to environmental conditions such as dirt, oil and water thatcan cause false readings, an increased battery life of 3.5 years under normal operationand Absolute (ABS) sensor that eliminates the necessity of setting the referencewhen the caliper is powered on. It is also fully compatible with existing Mitutoyo digimatic peripherals(SPC cables, U-Wave wireless transmitters, etc.).