Little Well brass 1/2'' Push-Fit X 3/4'' NPT Female Pipe Thread Coupling

The coupling features a lead-free solid brass body with push-fit connections to create solid seals and gives you a 3/4 in. Female NPT Adapter on the opposite end. Just insert the pipe and the inside stainless steel teeth bite down and grip tight, while a specially formulated O-ring compresses to create a perfect seal.

eBay