This item was discontinued by the manufacturer in late 2017. If you need to replace this part on an existing Guardian horizontal-mount plastic shower head such as item # AP450-032ORG, you will need to order BOTH a 300-12-08HB reducing bushing as well as a 300-08SE galvanized steel elbow to duplicate the function of the discontinued 330-12-08RSE street elbow shown here. This change to a 2-piece design is more robust than the older part. If you have a metal shower head you do not need the bushing, just the street elbow.
A parts diagram for Guardian showers is also available.