This is a 1921 instrument made for a left-handed player. Looks like a standard Conn design except for the left-handed part. It is done in silver with gold inlay - nice!! Nice hard case included. Condition is very fine. Buy-it-now price is only $609.
I BELIEVE THIS HAS SOLD FOR $609
https://www.ebay.com/itm/1921-CG-Conn-RARE-LEFTY-3-Valve-Satin-Gold-Euphonium-Baritone-Orig-Case-Mpc/323787904030