Image 3 Mask & Exhalation Port

Hi all,

I am using a Image 3 Mask for COPD. My Bipap Machine is Respronics Pro2.

Till Now I was using to conect this Image 3 mask to the tube via a exhalation port. The exhalation port had a hole and another nozzle for oxygen inlet.

I want to know if seperate exhalation port is necessary with Image 3 mask.
And where fo I buy the same online. CPAP.com does not have the require part on their website.

Thanks.

Shiva