Embassy of Nigeria
(Your company) is pleased to introduce (Applicant's full name & title) who is traveling to your country on (approx. dates of travel) for the purpose of (business discussions, or negotiations etc).
While visiting Nigeria, (applicant's name) will meet with representatives of (name and address of host company in Nigeria).
(Your company) hereby guarantees the financial expenses of the applicant while (he/she) is visiting your country and (his/her) return transportation to the USA. We appreciate the issue of the visa without delay.
(Signatory should be a Company manager, other than the applicant)