Here's a sample cover letter.  If you have a printer hooked up to your computer, cut and paste the letter into your word processor, fill in the "< >" appropriately and print it out. If you have a company letterhead, use it.

                                                                                                            <date>

<Name>

<Street or P.O. Box>

<City, State, ZIP>

<voice & fax telephone numbers>

New Jersey Feed Lab Inc

P O Box 06650

Trenton  NJ  08650

Sirs:

Please test enclosed <number> sample(s) for moisture, protein, fat and fiber.  Attached is a check in the amount of  <$dollars> for <number> samples(s) @ $33.50 each.  Return your certificate of analysis to the above address.

                                                                Yours,