Outdoor Water Solutions has re-engineered the old style pressure relief valve (picture on top) to a newer version made of all steel construction for longevity (picture on bottom).

The old style pressure relief valve used three 3/8" hose barbs with the pressure relief valve on the top. Unfortunately, rain and moisture could get into the open hose barb and cause failure, especially in freezing weather. The new style PRV mounts sideways and is made of steel so moisture is less of a concern.