This is beautiful old European Eb Tuba made c.1880  by "W. Stowassers Sohn - Graslitz" with four side action rotary valves (SARV).  It has a massive thumb ring and all ferules and valves are decorated profusely (see 2nd photo below). A unique feature on this tuba is that valve spring tension can be adjusted independently by a rachet wheel attached to each valve. This tuba has a big voice commensurate with it's size.

Bottom photo is of my long time friend, Bob Tucci (Perentucci Tubas)  having a blow on the mighty Stowasser, Jan 2010.