I bought one for my own electronics work. Later, since there was a discount, I bought a few extra from China, so I am selling the extra ones now (at a discounted price). FNIRSI DSO-TC3 3-in-1 Handheld Digital Oscilloscope, Signal Generator and Transistor Tester. This is a 3-in-1 device that can be used as a digital oscilloscope, signal generator, and transistor tester. It has 500KHz bandwidth and 10MS/s sampling rate. It is very effective for basic signal checking, waveform testing, circuit diagnosis, radio/audio circuit troubleshooting, and electronics experiments.