Sensor : ZMPT101B
Onboard precision miniature voltage transformer
Onboard high-precision op amp circuits for signal sampling and adequate compensation to make precise functions
Modules can be measured within the 250V AC voltage, the corresponding analog output can be adjusted
PCB board size: 49.5 (mm) x19.4 (mm)

Datasheet: http://www.zeming-e.com/file/0_2013_10_18_093344.pdf - See more at: http://www.ewallpk.com/sensors/1275-active-single-phase-voltage-transformer-module-ac-output-voltage-sensor-for-arduino-mega.html#sthash.EetNwH57.dpuf