You got people with your warranty cards, do you live in 2022 or where? According to the law "On Protection of Consumer Rights", the presence of a warranty card is not a prerequisite for making claims to a store or service center. In some cases, the buyer may make a claim without a receipt at all, confirming the fact of purchase with witness testimony. Got pros: I bought for a promotion for 3800, the price is a gift for two instruments. Build quality seems to be good. Its cons: Until I found out, they work. When I bought, I looked at the characteristics in such a way that I do not consider the absence of any functions to be a disadvantage. If someone lacks backlight, speed control, etc. buy more expensive stuff.