B1 Invitation Letter - Please Help - Doc Download

We are a small business in US and have outsourced our project to a company in Chennai, India. We are planning to invite their project manager for a couple of weeks to have him participate in meetings and gather requirements. He wants an invitation letter from our company to get the B1 visa. Would be great if you can post a sample invitation letter addressed to that person.
Thanks for the help.

BI visa format is available in the US consulate you can approach them they will give you a detail format as per their requirements

Hi,
Please find the enclosed B1 invitation letter.
Regards,
Sree Laxmi M

This is awesome. Thank you very much. I believe this letter should be sent to the US embassy in Chennai. Should we send the same letter to the person we are inviting or is there a different letter for him. If we should send him a different invitation letter, can you please send me that format.
Sorry for the trouble. Appreciate your help.

Can someone please post a sample document that we should sent directly to the person (not consulate) whom we are inviting over.
Thanks again for the help.