Here we have an A*600/5.6. While I don't know this to be true, I've always thought of the A*600 as a modified, slightly lengthened A*300. I had owned the A*300 and the A*1200 before receiving the A*600, and had presumed it would be sized somewhere between the two, but it's really quite small, not being that much larger than the A*300.
As you can see in the photo, the lens is very front heavy, to the point where it is almost unusable when attached to a tripod via the tripod mount.
A6005.6A6005.6A600 5.6Pentax A star
From Pentax A Star Series Telephotos