A seat or part thereof

As shown in figure 1 there is a torso support for a seat, having: * an padding base 2; * an outer link 3; * an inner link 4; * a U shaped clamp 6; * a release button 5; * a pivot pin 7; and * a seat attachment bracket 8. The inner link 4 has a space housing the button 5. The button 5 can be pressed so it pivots between locking and unlocking dispositions. When in the locking disposition the inner edge 13 of the button is close to a short arm of the clamp so they are almost abutting. This prevent the inner link 14 pivoting because to move in that way would cause a clash between the inner edge of the clamp 6 and the button 5.