The Spa Components 20-46-4033 heater assembly can be found in (but not limited to) Cal Spa hot tub systems (but not all)..
The Spa Components B24055G flo-thru heater assembly has the following features and specifications.
Manifold Length: 15.5"
Manifold Diameter: 2"
Heating Element Included: Yes
Kilowatt Rating: 4.0KW
Voltage Rating: 230V
Mounting Studs: Yes
Number of Mounting Studs: 3
Clip for Sensor: Yes
Temperature Sensor Included: No
Hi-Limit Sensor Included: No
Pressure Switch Included (A.K.A. Flow Switch): No
Number of Threaded Taps: 1
Threaded Tap Location(s): Pressure switch tap 9 O'Clock.
Tail Pieces Included: Yes (removable)
Tail Piece Size: 2" x 2" (removable)