While this item can be used independently, this gauge is designed as a replacement gauge spec'd to fit Firestone's Dual Path Control Panels (2.07" diameter), whether they are pneumatic or electric. This replacement is meant for both the metal & plastic control panels.
This item replaces the gauge for the following part numbers: 2241, 2260, 2574, 9201 Long Part #: WR1-760-9201