SpaGuts 25-150-0002 Universal Inline Bath Heater Kit, 1.5KW, 110V, 7x1.5 inches, with Built-in Vacuum Switch This is the 7.0 x 1.5 inch in-line style bathtub heater, designed to be installed on the VACUUM SIDE of the bathtub pump. This bath heater is normally meant for use on 1.5 inch plumbing, but can also be used on 1.0 inch plumbing when using the fittings that are provided (Vacuum Switch version is NOT for use on 0.75 inch plumbing). Inside diameter is approximately 2.375 inch for the black heater split nuts. FEATURES: Stainless Steel 7.0 inch x 1.5 inch in-line heater 1.5kw 110V Incoloy heater element Built-in vacuum switch to activate heating Automatic smart thermostat (104 degrees F limit) Reversible mounting Heater on light Hi-limit protection 1.5 inch and 1.0 inch pipe fittings included Pair of 1.5 inch Heater O-Ring Gaskets included 110V 60Hz 3ft NEMA cord Copper Bonding Wire included Installation and Operation Manual 2-year limited warranty UL Recognized for safety standards The Vacuum Switch model bath heater is also a replacement option for the following model numbers: 10-305-1655, SG101-15UV, 935213-23, 10-175-1655, PH101-15UV, 2-00-7516, 46-355-1054, CT100 (Vacuum Switch Models Only), C3B93P1-E012JUZ, S749000, S749, S750, H155000, H155, G130000, G130, DQ75000, DQ75, G903000, G903, U395000, U395, T180000, T180, G947000, G947 This bath heater is also a replacement option for the following brand bath heaters: American Standard, Safe-T-Heater, Hydro-Quip Compact Series Whirlpool Bath Heater, Jacuzzi RapidHeat, Pure Heat, Eljer 4941000-00, menards 6717550 NOTE: This bath heater is designed to maintain the current bath water temperature in the tub, and is not meant to heat water from cold to hot.