This D.O.T. Rated Fitting is 1/4" Male NPT to 1/2" Push to Connect Elbow. This will allow you to elbow off 1/2" airline to a 1/4" NPT Port.
This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.p65warnings.ca.gov.