Features:  - With DC dimming method, 4' full-view LCD screen can be seen more clearly for outdoor uses, and more comfortable for indoor uses.  - Optimized Electric Bridge: Making full use of the harmonics of Si5351, it can use the 5th harmonic to measure up to 1.5GHz.  - When fundamental wave is used, the output level of CH0 is increased to 0dBm, making reflection measurement more accurate.  - Solved the abnormality of NanoVNA-H when operating at around 6MHz before.  - Redesigned power management circuit reduces power noise, USB power interference, and charging current.  - Improved PCB layout.  - Reserved UART interface for DIY expansion.  - Lightweight ABS shell keeps the device well protected.  -Computer software supports control and real-time display. And it support for exporting snp files for various radio design and simulation software.  - As a measuring device, accuracy is of great importance. Simple calibration parts are included in the package. We have calibrated the product's dual ports before delivery. When your measurement conditions change (for example, switching from a narrower calibration bandwidth to a wider measurement bandwidth with an extension cable measurement), you need to re-calibrate. After calibration, it is saved as setting 0, which can be used directly at the next boot, or it can be saved to the other 4 saved items through recall when needed.     Specification:  1. ABS Shell: 75mm x 133mm x 18mm (excluding protrusions).  2. Measurement Frequency: 50KHz ~ 1.5GHz.  3. RF Output: 0dbm (±2dB, fundamental wave).  4. Frequency Accuracy: <2ppm.  5. Frequency Stability: <0.5ppm.  6. Measurement Range: 70dB (50kHz-300 MHz), (60dB (300M-900MHz), 40dB (0.9G-1.5GHz) enable expansion firmware).  (Note: Please pay attention to the error caused by nonlinear transformatiion of the fundamental wave when using harmonic measurement.) 7. Port SWR: <1.1.  8. Display: 4' TFT (320 x 480).  9. USB Interface: USB type-C; Communication Mode: CDC (serial).  10. Power Supply: USB 5V 200mA. Maxmum charging current 1A. 11. Number of Calibration Points: 101 (fixed).  12. Number of Scanning Points: 101 (fixed).  13. Display Tracking: 4, Marking: 4, Save Setting: 5.  14. Measurement of S-parameters, voltage standing wave ratio, phase, delay, Smith chart, time domain analysis, etc.     Package lIncluded:  1 x NanoVNA-H4  .  2 x 15cm SMA Male to Male RG316 RF Cables.  1 x SMA Female to Female Connector.  1 x SMA Simple Calibration Kit SHORT.  1 x SMA Simple Calibration Kit OPEN.  1 x SMA Simple Calibration Kit LOAD.  1 x USB Type-C Data Cable.  1 x Type-C to Type-C (For Android mobile phone connection)