Each switch module has 8 separate 4×4 matrix sections which may be interconnected to form a variety of larger configurations when used in the HDX chassis.   Most commonly used for Nx4, and Nx4xM configurations.  Uses D37S ( Socket ) connectors and type A armature relays with the following specs:

TYPE A RELAY SPECIFICATIONS

• Switching Voltage 110 VDC
• Switching Current 1.0 A
• Carrying Current 2.0 A
• Breakdown Voltage 750 VDC
• Operate Time 3 ms
• Lifetime (mechanical) 100 million cycles
• Lifetime (electrical) 10 million cycles @ 10 VA
• EMF < 3 uV