This is the PayPal Pro US payment gateway for nBill.
This PayPal Pro US payment gateway for nBill uses the direct and checkout methods for transmission of information. The user is redirected to the PayPal site for express checkout processing OR can remain on your site and enter their credit card details.  After express checkout processing, they are then returned to your site to continue the process. 
Special Requirements: SSL certificate.
Osdcs.com can develop just about any payment gateway, so if you can't find it, just ask.