Comptus A70H-USD Ultrasonic Wind Speed and Direction Sensor The A70H-USD does not have any moving parts, needs no maintenance, and has no on-site calibration. In order to get the most out of your instrument, we recommend you read the manual provided upon delivery carefully before installation. #ultrasonicwindspeedsensor #comptus for more: https://www.comptus.com/products/wind-ultrasonic/