Abstract: An auxiliary feed hopper for permitting the trimming, in a saddle binder, of perfect bound books which includes a horizontal base plate having a pair of longitudinally extending slots. The base plate is supported above the delivery bed with the slots in register with the lug slots normally provided in the delivery bed. A rear stock plate is secured to the base plate, and supporting brackets at the side edges of the base plate are clamped in positions equally from the stock plate. A front stock guide is provided including a bridge spaced above the base plate, the bridge being supported at its ends upon the brackets. Side stock guides are spaced parallel to one another on the base plate, the guides all being adjustably movable on the base plate for receiving, between them, a stack of perfect bound books. A barrier adjustably secured to the bridge, and projecting downwardly therefrom, forms a gap to permit the lowermost book in the stack to feed under the bridge while holding back the remainder of the stack.