Abstract: Apparatus for indicating the thickness of a document being fed along a feed path comprises cooperating upper and lower roll sets (20 and 32) between which a document passes. The lower roll set (20) is driven by the document transport, while the upper roll set (32) is rotatably mounted on a pivotally mounted arm (36), which is urged by a spring (42) to cause the upper roll set (32) to move toward engagement with the lower roll set (20). The upper roll set (32) includes a central cylindrical portion (30) of reduced diameter. A further roll (46) is mounted so that its circumference is normally spaced from the surface of the cylindrical portion by a predetermined distance. A timing disc (52) is mounted for rotation with the further roll (46), and a sensing device (58) is associated with the timing disc (52) to generate pulses as the further roll (46) rotates.