rueda para graduar el respaldo
/ruˈeða pˌaɾa ɣɾaðwˈaɾ el respˈalðo/
n
English: adjustment knob · 调节旋钮
Significado：The seat’s regulating mechanism, for changing the angle of the backrest to an almost horizontal position.
English: adjustment knob · 调节旋钮