Hydro Super 2 Up to 2 ltrs per min of hydrogen/HHO. Engine size 1 to 3.8 ltrs Gas or diesel. Up to 40% gain in MPG because now you are adding a supplemental fuel. Plus your adding oxygen to help every thing burn more complete, and hydrogen/HHO to ignite every thing in the combustion chamber. This unit is built to last. Made right here in the USA. $389.00 Hydro Super 2 Double Hydro Super 2 DOUBLE unit Is a Complete HHO / Hydrogen generator ready to install. For 3.9 ltr and larger gasoline or diesel engines. Draws only 13.8 volts DC and 14 amps on each cell. This unit only heats up 30 to 40 deg over 10 hours of continuous use. 3.7 to 4.2 ltr per min of HHO depending on mix. Most Over the Road trucks Use 2 of these to see 1.5 to 2 MPG gains. This is the real deal and and built to last. Made here in the USA!. $589.00 o2 Extender This is the O2 sensor Extender it backs the O2 sensor back out of the exhaust pipe 3/4". So Your oxygen sensor will not pick up on the extra oxygen. Then compensate by sending more fuel to the engine. This way the HYDRO SUPER 2 unit will produce the max MPG gains for your vehicle. NOT for some Toyota or Saturn cars. Please check to see how many o2 extenders you will need before you order. Also read our will it work on my car page before you order. Made here in the USA!. $10.95