The Astron Mark was the second kit Estes produced (K-2). It was one of the few kits to use BT-30 tubing. I bought my Astron Mark in 1970 but never flew it. When Semroc released their xKit version of the Astron Mark, I bought one of those and launched it. Here's pictures of my original Mark and my Semroc xKit Mark. One picture includes the instruction sheets for each kit.