Dear Mr. Cartagena,
I saw your ad on your website for a Field Engineer with experience. I am that person, and have included my resume.
I know I am the right person for this opportunity as I have over five years experience working as a dedicated Field Engineer for Eaton Corporation. In that role, I served the company by analyzing and troubleshooting all power needs for this large scale factory chain; and did so with the right expertise and skill. I work great in a team setting and am a great communicator.
Thank you for your time. I can be reached at (555)-555-5555 for more information.