virole

plural viroles

1. governmentA ring surrounding a bugle or hunting horn.

   […] except when he has a hood, bells, virols, or rings, and leashes, in which case he is said to be hooded, belled, jessed, and leashed; […]

   1836, Sir Daniel Keyte Sandford, The Popular Encyclopedia;: pt. 1: England-Germany (literature and science), page 698

   2 more examples

   The Florentine GUICCIARDINI bore : Azure, three hunting-horns argent, the mouth-pieces and viroles or, banded gules. Gules, three trumpets fessways in pale argent, is the canting coat of CALL (Baronets).

   1892, John Woodward, George Burnett, A Treatise on Heraldry, British and Foreign: With English and French Glossaries, page 386

   Viroled- (vi-rold') Furnished with a virole or viroles. Said of a bugle or horn when borne with rings of a different tincture from the bugle itself.

   1908, Arthur Francis Pimbley, Pimbley's Dictionary of Heraldry: Together with an Illustrated Supplement, page 67