This blade is great if you want to create a 'tear off' in your invitation layout. For example, if you want your inserts to layer evenly and do not want to worry about your RSVP being 3.5x5, make your insert any height and Perforate it so your guest can tear it at the correct size and insert it into your RSVP envelope (or send via postcard!) Works with your Paper Buddy Rotary Trimmer & Handheld Rotary Trimmer