Parker 171HD-6-4 Flareless Tube Fitting, Hi-Duty, Tube to Pipe, Brass, Compression and Male Pipe Run Tee, 3/8" and 1/4": Amazon.com: Industrial & Scientific
Flared vs Flareless Fittings - QC Hydraulics
Flareless Bite Type Fittings, Flareless hydraulic and pipe fittings