Second on the electronic fuel guage, but I ran out of $$ for the 260.00 electric NO2 guage so I went with the manual, not a huge deal, but you do waste a bunch of no2 through the lines to the guage and at 50.00 a 10lbs bottle, in time it will add up, but I just could not justify spending two hundred dollars on something that did not make me faster or safer, and this guage does niether. Especally if you have an nx heater with a pressure switch on it, because it will automatically shut it off at high pressure, and if you only using it at the track, the bottle pressure guage would be just fine and cheap. Besides to many guages is ricey IMO.