Ammeters measure electrical current (in Amperes) flowing through a circuit and therefore are wired in series with the load. They are useful when using a dynamo based charging system, as they can warn the driver (for example) of negative charging conditions. The 60A rating is also suitable for alternator charging systems where the rating of the alternator is less than 60 amps.
The gauge is supplied a 'U'-shaped fixing bracket and thumb nuts along with a 12v /2w illumination bulb. Night illumination is classic white.
The gauge size of 52mm denotes the outer diameter of the main body of the instrument and hence a 53mm to 54mm diameter hole is required in the dashboard.
52mm Ammeter wiring diagram here.