There are some tools that you can buy cheaply. The edge finder just isn't one of them if you want it to work the way it's designed. So spend the extra $10 on imports, your accuracy and repeatability will thank you!
Digital multimeter RGK DM-12
6 Review
π¬οΈ Advanced 3-in-1 Indoor Air Quality Monitor with CO2/RH/Temp Data Logging and Audible Alarm - NDIR Sensor Technology
8 Review
π Enhanced Precision with Backlit Professional Manometer for Differential Ventilation
6 Review
π Dioxide Controller for Digital Gas Monitoring
5 Review