What can be fitted inside a brass instrument to change its sound?

Brass instruments can have various devices fitted inside them to alter their sound, with the most common being mutes. Mutes are devices made from materials like metal, rubber, or plastic that can be inserted into the bell of the instrument to dampen or modify the tone. Additionally, players can use different mouthpieces to affect the instrument's timbre and response. Each of these modifications allows for a diverse range of sounds and tonal colors.