In the late 80’ies there where two big brands competing to be no 1 in the MTB group business: Shimano and Suntour.
In 1990 Shimano was performance wise slightly ahead of Suntour while Suntour components where slightly lighter and less smooth at shifting.
Always one step behind Shimano (depending on how you view the situation), most Suntour gear where actually good performing, dependable and highly usable if not slightly dull and unexciting.
This Suntour XC-Comp rear derailleur is the equivalent to the Shimano Deore DX rear derailleur, i.e. it was positioned one step under the best group offered by the company.
Suntour had a reputation of not offering the same smooth shifting as Shimano had, ironically in this case Suntour where most famous for their good front shifting, the ultimate combo back in 1990 would have been an XT rear system with a Suntour XC-Pro front system.
Comparing the DX rear derailleur with the XC-Comp it is highly evident that the XC-Comp has a slightly better finish and just feels and have the look of a more professional component, it also feels a bit lighter, but by how much? (I don’t know).
In good condition with some scratches, 30 euro. Sold