Tubing
Columbus made far more than SL and SLX. SP stands for Strada Pesante, heavy road, with walls of 1.0/0.7/1.0 mm, and Columbus recommended it for large frames. SPX is SP with the SLX spiral ribs. Columbus also made lighter sets for time trial and track bikes, the oval Max set in Nivacrom steel around 1990, and plain straight-gauge tubing for amateur and touring bikes. The dove decal looks much alike across all of them, so read the set name where there is one and check it against the model's catalog. On a big frame, SP was the tube Columbus meant for it, and it's no step down. On a mid-range bike, a Columbus decal tells you less than it seems.
3 models we cover.
Colnago
Other Columbus tubing$1,025–$2,825 typical ask
18 on eBay
Colnago
Other Columbus tubing$1,225–$2,175 typical ask
100 on eBay
Bianchi
Other Columbus tubing$525–$725 typical ask
20 on eBay