The phrase "a device that indicates" is correct and usable in written English.
You can use it when describing a tool or instrument that provides information or signals about a particular condition or status.
Example: "The new smartphone features a device that indicates battery life, ensuring users are always aware of their power levels."
Alternatives: "a tool that shows" or "an instrument that reveals".
Flow indicator means a device that indicates whether gas flow is, or whether the valve position would allow gas flow to be, present in a line.
In 1820 Daniell invented a dew-point hygrometer (a device that indicates atmospheric humidity), which came into widespread use.
He needed a blinking door signal, a device that indicates when someone is calling up to his apartment.
As the birds enter their home lofts, the band is removed from the leg and placed in a timing device that indicates the time of arrival.
Women were also trained in the use and interpretation of the Clearblue® Easy home pregnancy test, a digital device that indicates the test result as either pregnant or not pregnant.
Controllers said they did not receive a signal from the Legacy's transponder, the device that indicates a plane's speed and altitude.
Railroads already have begun to phase out the caboose, replacing it with a $4,500, shoebox-sized electronic device that indicates whether the train's cars are attached and their brakes are working properly, functions once performed by men in red kerchiefs and overalls.
Beacon, signalling object or device that indicates geographical location or direction to ships or aircraft by transmitting special radio signals, or a conspicuous object, either natural or artificial.
The reproducibility of the stimulation coordinates across sessions was guaranteed by a virtual aiming device that indicated in real-time any deviation from the desired target greater than 3 mm.
The pennant was the device that indicated a ship was armed and commanded by a navy officer.
It is a cockpit device that indicates the flight path on a horizontal scale of light bars and the angle of the wing on vertical scales.
