First of all, it has been 20 years since Shi Jian was founded. If it is not good, it will not last so long.
Second: the founder of Shijian has been invited by Beijing TV station many times. If it is not good, it will not be on the show many times.
Third: the products and tools used in stone reduction were invented by its founder. If it is not good, there will be no such invention!
Everyone has a different opinion! I hope I can help you!