A ring binder

A ring binder comprising a substantially rigid curved upper casing structure supporting a pair of plate, and the plates are pivotally movable between a first position in which the angle between the upper surfaces of the plates is less than 180°, and a second position in which the angle between the upper surfaces of the plates is more than 180°, a lock to lock the pair of plates and triggers or a pair of half-ring members to operate the lock, and the lock acts at a first location on the ring binder and the triggers or pair of half-ring members act at a second location on the ring binder, the first location being longitudinally distal on the ring binder from said second location.