The mark “1/4” on the valves body is the inner side of the valve, not the barb size. Insert the barb into the tubing, and fix it with a pipe clamp for a tight seal. Constructed of durable and corrosion-resistant brass. Rubber-covered operation handle for non-slip control.
If the barb is too large for the tubing, you can dip the tubing into boiling water or use a hot air gun. A little bit of heat would help to expand the tubing to fit perfectly.