I tried ordering the metallic one and it was out of stock. Marcus sent me two dennerle's and I do have to say they are excellent quality for check valves. I have turned off the solenoid and not noticed any backflow (not sure there was any at all since I have black co2 tubing) that came into the bubble counter. Solid construction on the dennerle's, they have plastic locking nuts on the ends where the tubes connect into.
Member #6 of the Eheim Pimp Club - 2 Eheim 2213 & 2215 w/ surface extractor, LiquidDoser and Auto Feeder.