The Part Number is SOM-NI (Special Order with Mailer). This is a three-part Special Order Form with the last copy being made of card stock. Once the special order item has arrived the top part of the card is detached and mailed as a postcard to the customer indicating that the item has arrived. The bottom part is attached to the item or filed. The SOM-NI is identical to the SOM-IMP except it does not have your Company Information imprinted on the form.