H1B Visa interview -Middle layer vendor letter sample needed

I am planning to go for Visa interview in India(Hyderabad), I have client letter and employer letter for employee employer relation to show up, but can any one send me middle vendor sample letter to carry( I have 2 layers in the middle from my employer to end client ) , incase Visa office asks I can able to provide that info to them.Thanks for help.Ramesh