Testing Renix Coolant Pressure Bottle, Adapter?

[knever3]

I have a Stant pressure tester, but don't have the required adapter to go to the traditional radiator cap.  I have seen one FZ25 cap adapter, but at $41 I could almost buy an entire 25 piece kit with a pump.  I am sure to use it on more vehicles in the future, but don't really NEED it at this time.  I would like to pressure my system up to see if I have any leaks since I smell coolant.

 

Please post links.