Our FE390A is just like the FE390, except we took off the barbs and left the fittings up to you. So many of our customers wanted this option, we decided to make it a kit and allow other people to get creative! Works well with our polysuphone QD's. The unit features a stainless thermometer, stainless tee, and a stainless oxygenation stone. The barb on the stone is 3/8". How long should I apply oxygen while transferring to the fermenter? We recommend you transfer half of your wort to your fermenter before applying inline oxygen (O2) to your wort transfer. If you apply O2 the whole time while transferring you are wasting O2.