The item number is 1812Y4K00151KXT and it refers to a ceramic capacitor. This specific capacitor has the following characteristics: 150 picofarads of capacitance with a tolerance of ±10%, a maximum voltage rating of 4000 volts (4kV), and an X7R temperature coefficient. It is packaged in the metric 4532 size, which is equivalent to the 1812 size in imperial units.