The acrylic cap glues onto the acrylic tube via a UV activated glue.
Step one: Bend all your tubing
Step two: Pass the compression ring over the acrylic tube
Step three: Glue the acrylic collar to the tubing
Step four: Screw the fitting into the block
Step five: Screw the compression ring into the fitting
Once the compression ring is screwed into the fitting the compression ring pushes the acrylic collar against an o-ring attached to the fitting, creating an fluid tight seal.