When precision counts, count on the CombBind™ C450E's exclusive "Paper Centering System" combined with vertical feed to align paper for perfect punching. One-touch electric punching is easy and efficient. For letter size documents. Rotary dial for control of comb opening and closing. Electric punch operation. Binding Spine Type: Comb; Binding Sheet Capacity: 500; Punching Sheet Capacity: 25; Maximum Binding Edge: 11".