What I recall is that Columbus sold a whole set of SL (9/6/9) or SP (1/7/) in a group package. It would contain all 11 tubes. The "A" package would have 600mm main tubes, the B would be 620 and the C would be 650. The steerers also varied in length (the A being 200mm if I remember right) as well as the seat stays. The earlier models had the Columbus insignia and whether it was SL or SP stamped into the tube. Later they just chemically etched it on.