A comment
My husband and I changed the door about a month ago. They scoured the entire Internet, interrogated all the friends, stopped at the Guardian. For a long time they could not decide on a model. Choose between DS-3U or DS-9. The DS-9 has better sound insulation, but the DS-3U had an armored package and one more stiffening rib, and indeed in the basic configuration the largest, and the price is slightly lower. Therefore, we decided to stay on the second option.
We went to the office on Timiryazevskaya, there they still looked again, as if we had decided on the choice. We chose the finish, the manager explained everything correctly and helped. The husband insisted that the door was ugly - as if the thieves would think that we had nothing and would not come to us))) The price was not small, but acceptable. After 2 days the measurer arrived. A calm man, did not impose anything, did not bother, calmly worked and answered questions. Quickly issued a contract.
Then, after a while, the installers arrived. At first everyone measured the level for a very long time, I don’t really understand everything about it, they welded something, installed it, then tinkered with the opening. As a result, now everything is in order: it has become noticeably quieter, it has stopped blowing, everything is in order with the locks. So I can recommend it.
pros
The sound and thermal insulation, the reliability of the locks have improved. Door specifications
Minuses
For myself, I did not find any special minuses