caveat emptor: kit came with 3 resistors of 120 kilo-ohm instead of the required 120 ohms resistors, so i had to replace these
product o.k. for quick and rough look at waveform. Tested using a function generator and sawtooth/triangular, square and sinusoidal - all o.k. upto about 8KHz. Negative part of waveform distorted when amplitude increased (probably need to calibrate probes). Order took usual time to arrive from China. For how much it cost, a very good product.