This part of 60444 explains the test fixture that allows the accurate measurement of resonance frequency, resonance resistance, and equivalent electrical circuit parameters of a leadless surface mounted quartz crystal units using zero phase technique as specified in IEC 60444-4 and IEC 60444-5. An equivalent circuit constant and the application frequency range obtained by using the test fixture are then shown. In addition, this is applied to the enclosure shown in IEC 61240 as a crystal unit without lead wires. An equivalent circuit of the test fixture and an electric values are based on IEC 60444-1 and IEC 60444-4. The range of load capacitance is 10 pF or