I have just assembly my holder. Good product but I my opinion it needs some changes. The angular connectors have to big wholes and I used additional washers to make holder stifer. Using holder with nuts inside profiles as rails is realy hard. They are blocking all the time. I have change them for t-nuts (attached picture) and now it works great!
All parts arrived! But it does not come with correct nuts. And you have to order apart. T20-M5