There are four different tuning slides available. The horn is manufactured as standard with tuning slide 1 for all 440 Hz keys. The other tuning slides 2,3 and 4 for historical keys are optionally available. Tuning slide 2 for 430 Hz keys from C-alto to E, tuning slide 3 for 430 from Eb to Bb-basso, or for 415 Hz keys from C-alto to E and tuning slide 4 for 415 Hz tunings from Eb to Bb-basso