These fuel pressure gauges are designed to pair perfectly with both ACUiTY's fuel rails, as well as most other aftermarket fuel rails with 1/8 NPT gauge ports. To guarantee a quality product, ACUiTY has industry leader, Marshall Instruments, produce these gauges to ACUiTY's specifications. These fuel pressure gauges feature rugged construction and are liquid filled for vibration dampening. This model features a 1/8 NPT thread. The gauge features a black bezel, red pointer, and satin black, powder-coated, steel case. The max bezel diameter is 1.75" and is the perfect size to pair with an ACUiTY fuel rail.