Thermometers feature a 1/2" NPT threaded connection (H-B Catalog No. 21596 features a 3/8” NPT threaded connection ideal for industrial installations in tank or pipe lines.) and polycarbonate lens (H-B Catalog Nos. 9/5200 and 9/5030 feature a glass lens). External adjustment allows for simple field calibration. For correct temperature reading, stem must be immersed at least 50mm (2") in liquids and 100mm in gases (4"). Each thermometer is individually packaged with a multi-language (English, French, German, Italian, Portuguese and Spanish) Statement of Test and Calibration.