Product review (5 stars): Meticulous surface prep is the key
Most of the comments I could make have already been said. For an inexpensive price you can repair/evacuate/recharge any product using Freon rather than throw away when there's a problem in the sealed system.

Some people knock this valve saying eventually they will leak. The directions that Supco provides leave a lot to be desired. They don't say anything about preparing the surface of the tubing on the intake side of the compressor. The BPV31 comes with a thin gasket material. To seal properly, the tubing MUST be cleaned and finished to a shiny surface to enable the valve's gasket to seal tightly. Freon molecules are teeny tiny. You do NOT want any scratches on the tubing or the Freon will find it's way out those scratches. Because of this, I would NOT use most types of sandpaper or steel wool to prepare the tubing.

What I did that's working two years after repairing my home freezer using R134a is very carefully prepare the surface of the tubing. First I located a several inch long section of straight tubing on the intake side that was perfectly round and undistorted. Next step was to clean it with progressively finer Wet or Dry 3M paper. I did it wet because that keeps the paper from clogging up with copper particles. I started with 600, went to 800, 1000, 1500 and finished with 2000 grit paper. It might be overkill, but I finished up with automotive polishing compound. This left the tubing shiny as a mirror. The smoother the surface the better the valve gasket will seal.

The last step was to install the valve. I tightened the three Allen bolts which attach the valve very snug and kept them even by going around several times getting tighter each time much like you would tighten lug nuts on alloy wheels. After pumping a vacuum for an hour or so and recharging with an ounce of metal leak seal followed up with 5.3 oz R134a, the unit is freezing as good as new two years later.