The 110 Volt plug-in model gives great showers for those areas that do not have conventional hot water making equipment available. The iHeat Tankless Electric Shower Head is also available in a hard-wired model using 23 Amps at 220 volts. The 110 Volt AHSH2500 unit is UL#499 compliant and ETL#834 listed and is Intended for use in homes, apartment, condos or where ever you need hot showers. This unit offers 1.0 to 1.5 gallons per minute using a small 110 volt plug per owner's instruction manual offered with this unit. The Shower Head easily converts to 1.0 gallons per minute for even warmer water. Note that this will not offer a hot shower in areas with less than 75 to 80 degree incoming water supply The more powerful AHSH5000 Electric Shower Head is available but not UL#499 compliant at this time.