Making a precise inhibition zone measurement (100 µm resolution) manually can become a challenge. The Haloes Caliper helps to perform this in a simple and precise fashion while avoiding parallax errors in readings. Pharmaceutical and clinical labs involved in inhibition zone measurements benefit from the use of this device. A precision rotating wheel accurately measures inhibition zones while being manually spun. This comes in handy during antibiotic susceptibility testing and antibiotic potency measurements.