The right thumb operates four keys. The uppermost key is used to produce B2 and B3, and may be used in B4,F4, C5, D5, F5, and E5. The large circular key, otherwise known as the "pancake key", is held down for all the lowest notes from E2 down to B1. It is also used, like the whisper key, in additional fingerings for muting the sound. For example, in Ravel's "Boléro", the bassoon is asked to play the ostinato on G4. This is easy to perform with the normal fingering for G4, but Ravel directs that the player should also depress the E2 key (pancake key) to mute the sound (this being written with Buffet system in mind; the G fingering on which involves the Bb key – sometimes called "French" G on Heckel). The next key operated by the right thumb is known as the "spatula key": its primary use is to produce F2 and F3. The lowermost key is used less often: it is used to produce A2 (G2) and A3 (G3), in a manner that avoids sliding the right fourth finger from another note.