Brass Push>Connect Tube Fitting, 0.25 Inch Tube OD To 1/4-18 Male NPT, Straight

PT240 polyethylene is one of the listed compatible tube types for this fitting, so you're good there. Push the tubing straight in until it seats and you're connected. No tools needed, and when you're ready to pull it apart, just depress the collet ring to release. For a quarter-inch OD tube going into a 1/4-18 male NPT port, this is a clean, straightforward match.

Fit-wise it matches 0.25 inch tube OD on the push to connect side and a 1/4-18 male NPT thread on the other end, so it’s meant to push onto 1/4 inch OD tubing and thread into a 1/4-18 NPT female port.

This fitting is designed to work with PT230 and TP160 nylon tubing, as well as PT240 polyethylene tubing.