This is the Yamaha Corporation [Musical Instrument Guide] website. This article contains information about the Horn [Choosing a Horn:The tone is affected by the material]
Wind instrument - Wikipedia
The Brass Instrument Family: French Horns, Trombones, Low Brass - Vanguard Orchestral
Choosing a Horn:The tone is affected by the material - Musical Instrument Guide - Yamaha Corporation
Yamaha YHR-668II Professional Double French Horn - Nickel-Silver
Brass instrument - Wikipedia
C.G. Conn 6D Intermediate Double French Horn - Lacquer
Brass Instruments and How to Compose or Orchestrate for Them
Exquisite material selection and precision welding result in better tone and accuracy, and smoother gas flow, creating an overall high-end atmosphere.
Bb Tone Brass Gold Lacquer French Horn 3 Cupronickel Piston Marching French Horn With Mouthpiece
Choosing a Trombone:Choosing by material - Musical Instrument Guide - Yamaha Corporation
Yamaha YHR-567 Geyer Series Intermediate Double French Horn
What's That Spot? Identifying Marks on Your Brass Instrument – Houghton Horns, Brass