2.0 Inch PVC street elbow, with built in thermowells for temperature sensors. Includes one long thermowell for a maximum 5/16" diameter sensor, and one short, for a 3/8" diameter 1" long sensor. This elbow was widely used on thousands of Cal Spas, and is commonly required for repair of a freeze-up.
To replace this part on a CalSpa (and sometimes other spas), you will also need this:
Heater Union