Function o f the Extra Keys on Rotary Trumpet ETC The extra keys found on many rotary trumpets are used in the following way: Each key can be used to decrease the resistance, and greatly increase the ac - curacy and security of a series of tones in the upper register. Each key is designed to affect a specific chord, and are easily engaged by the last finger of the right hand - at the same time that the valves are depressed for the the desired note. Alternate fingerings work as well. These keys can be fitted on both B flat and C trumpets. Most instrument are equipped with the following keys: Water key (B flat key): F, B flat, D and F A key: E, A, C#, and E "Vienna C Key": E flat, A flat, C and E flat A fourth key is also available: B key: F#, B, D#, and F # (The keys are most commonly used to help with the middle two notes of each chord)