The Martin Yale Premier 1632 letter opener is a truly innovative machine which automatically feeds and opens a stack of envelopes. Continual feed of up to a 1 3/4 inch tall stack placed in the feed tray Hands-free operation, just put envelopes into position and turn on Operates at a speed of up to 7,000 envelopes per hour Ideal for small to mid-size businesses Blades are fully enclosed to protect fingers Non-skid feet Manufacturer Reference: 1632