RF Filter:they are fitted to the metal case of the RF module on holes where the wires enter the system....

RF Filter:

feed through capacitors(EMI/RFI Filters) are fitted to the metal case of the RF module on holes where the wires enter the system. They let the signal pass through but will stop the RF from escaping from the device through that hole to the outside wiring.

1.Temperature Feature:        -55 C ~ +125 C
2.Caps and Tolerance:         1000PF  +80%  -20%
3.Dissipate Factor:               <3%
4.Insulation Resistor:           >3000 M Ohms
5.Rated Voltage:                  400VDC
6.Withstand Voltage:           800VDC
7.Circuit Type:                      C Type