Three main parts
The bass flute, like the concert flute, has three main parts: head joint, foot and body.
Main joint
The main band is the mouthpiece of the flute and the bass flute is curved in the shape of a J. Otherwise the instrument would be too long to play effectively.
Body
The bass flute body is the longest part of the flute and contains the majority of the keys, which the fan presses to create different notes.
Foot
The base of the bass flute is usually a C-foot, as opposed to the B-foot often used by concert flute players. Using a B-foot on the bass flute is to make it even longer and heavier. After playing for about 20 minutes, you will probably need to take a break.
Trill keys and rods
The bass flute gives some unstable notes when a player ascends a scale, so some manufacturers add keys to help a player compensate. Manufacturers sometimes also provide support bars with the instrument to help a player compensate for the weight of the instrument. A bass flute is a member of the flute group of wooden winds, which are all hollow tubes closed at one end. The bass flute has an octave below the concert flute, which has an interval that starts at the middle C, but many flutes have a special foot that allows them to play B below. There is a Renaissance instrument called the bass flute, but that instrument is set to G instead of C.
Source:danspela.com