Features: Black aluminum shell: mechanical appearance, good texture Digital mechanical: accurate measurement, real-time feedback, circular designs, and clear data display. Tight packaging: the embedded hygrometer+embedded pneumatic connector is tightly installed with good sealing performances. It can be installed on tube: different from other hygrometers, it can be installed on tube, and the humidity detection in space is more accurate. Small and portable, saving space Specifications: Component:Metal+Plastic Type:1Pc/2Pcs/4Pcs Size:Approx.30mm/1.18inch Package Includes: 3 Optional Package: Package 1 Include:Approx.1Pc Drying Box Hygrometer Package 2 Include:Approx.2Pcs Drying Box Hygrometer Package 3 Include:Approx.4Pcs Drying Box Hygrometer note: 1.Please allow 1-2cm errors due to manual measurement, making sure that you not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual of the item. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.