Rochester Gauges Spiral Gauge. Tank depth should be at least 1/2 to 1” greater than the length of the gauge. The additional depth may be considered "reserve" at the bottom of the tank that will not be measured.
Designed for top mount
1-1/2” MNPT tank connection
Suitable for up to 25 psig maximum
UL Listed for flammable liquids when gauge is 36” or less