HydroQuip Water Pro Series Smart Heater Plus - Replaces 6500-301 (1995 - 2000), 6500-310 (2000 - 2007) Water Pro Series “Smart” Heater, Titanium 5.5kW, 230V Standard Features: Barb Protection - to prevent damage High Limit Tripped Light Heater On Light Universal Adapter Plug Cross Reference Label Provided on Heater Plug-n-Click Heater Wires Fork Terminal Heater Wires 14 Removable Screws - for easy serviceability Attention: When replacing an old style heater you are required to replace the high limit sensor due to a change to a smaller diameter drywell. 59-455-1204 Plastic Smart Heater as used in Sundance Spas from 2000 to current. 3/4" barbed, high limit thermo-disc, and necessary wires for connecting to control box.