IEC1000-4-2 distinguishes four maximum discharge voltages (Table 3). In addition to the contact discharge test required by the HBM test method, this method also specifies an airgap-discharge test. Moving the test electrode rapidly and (if possible) in line with the pin to be tested, the air-gap-discharge technique approximates the so-called “ESD pistol.” It causes a spark discharge at a certain distance from the pin. In the contact-discharge technique, the ESD pistol is brought in contact with the pin to be tested before initiating the discharge.