Here is the description from Online:
Genuine Balboa® Stainless Steel Flow-Through Hot Tub Heater Assembly comes complete with pressure switch, split nuts and tailpieces. Used on Lite Leader/CAT100/CAT200/CAT300 and all Pre-97 style systems with externally mounted heaters. May be operated at 240V or 120V.
• 4kW @ 240V - 1kW @ 120V
• 2" Slip Socket (convert to 1.5" with BX9901 reducer bushings)
• Pressure switch installed
• American-made craftsmanship
Product Notes: Older units (obsolete) had white unions.