Alexander has been making horns for well over 100 years and it is STILL a family owned business. They know what they're doing - thus the reason the the huge majority of hornists in German play them. This is a gold brass descant with a stopping valve. The compression is 2.1 and that is over 6 (SIX) valves so that is quite impressive. An Alexander flipper has been added for comfort, and the bell ring is also made by Alexander. It's made of unlacquered gold brass and is all original with the exception of the 2 Amado waterkeys and the aforementioned flipper. The gold brass is slightly darker than the yellow brass version which gives it a better matching sound on the high F side of the horn (though, for some reason the 2nd slide is yellow brass - they probably missed that!). The stopping valve ensures good intonation because, as we all know, hand stopping on the Bb side of a horn (without one of theses valves) is treacherous.
Play that B minor mass with confidence. This horn was owned by a member of an internationally regarded U.S. orchestra and has been well maintained. There are the expected small dings and tarnish, but nothing major.
The case is a much older Atkinson MB1....