Bienvenido Roberto! all the way from the Canary Islands!
I found some information via google:
1)" Columbus does have some light-weight straight-gauge tubesets (eg "KL" and "Record") but these are intended to be specialty items for time trials and record attempts. You're not likely to see them used on a production bike. There's also a couple heavier straight-gauge sets ("Aelle" and "Zeta") intended for inexpensive frames......"
2) and, an ad for a "Oschner Mid 80s Columbus Zeta Tubing 63 1/2 cm c/c Metallic blue ........."
Angel Garcia
Long Valley, NJ