This is a post US Civil War  Over The Shouder (OTS) Tenor with side-action rotary valves (SARV) employing mechanical linkage.   Foreign made OTS horns were imported by both Union and Confederate bands during the Civil War 1861-1865.

The OTS horns were configured  so that the music would waft backwards towards the marching troops - with the band in the lead.   This design quickly fell out of favor after the war as band leaders finally realized that the troops march to the drum beat anyway - and that the music was better heard by the admiring crowds using bell-front configurations.

This horn was made by B. Cazzani & Co of Milano Italy- and was likely imported well after the end of the war by T. Pirone, New York. Cazzani made woodwind and Brass instruments in Milano from late 1800s to 1912. The bell is inscribed Premiato Stabile and Esportazione Mondaile and has a logo containing words Ditte Riunite The horn plays easily and clearly and the valve action  is fast and accurate. The use of a water key is indicative of a manufacture date after the US Civil War.