Butler Tray Hinges with rounded ends are a popular hinge used on many old and new tables. These hinges are specific to tables or trays with folding leaves. Hinges hold leaf in upright 90 degree position or open to support leaf in flat 180 degree position. As each leaf requires 2 hinges they are sold by the pair. When ordering 1 you receive 2 hinges.
Recently butler tray hinges have been used for keyboard trays on computer desks. Hinge allows drawer front to open flat for keyboard, when in use, and fold upright when not in use.
Butler-style coffee tables have four small half-round leaves, one on each side of table top. Each leaf requires two hinges/ one pair. A total of 4 pairs of hinges is necessary to redo an entire table. See picture below.