Siji Muge vacuum tubes are divided into two types. One is called aerospace tube and the other is called crystal diamond aerospace tube. The first is engraved with the word aerospace tube and the Siji Muge brand on the upper third of the tube. The latter has two graduations on the tube: twenty-five years and 250 degrees. The water tank and stand of the Siji Muge are not much different.
Another thing to note is the length of the vacuum tube. Vacuum tubes of this brand are divided into three types: 1.61.8 meters and 1.9 meters.
I have never seen the series you are talking about. However, the price of 16 space tubes with a length of 1.8 meters on the market is expected to be between 2,000 and 2,400 yuan.