RD Microwaves Inner-Outer DC Block has only 0.3dB insertion loss over the full frequency range from 500-6000 MHz at power levels up to 100 Watts average and 3 kWatts peak. Minimum DC withstanding voltage is 6000 VDC with high isolation of DC and frequencies below 500 MHz on both the inner and outer RF conductors. PIM performance is better than 160 dBc over the communications bands making it ideal for leaky cable antenna systems in tunnel applications where high static voltage is generated by moving railway cars. The unit is provided with either 7-16 DIN connectors or 4.3-10 male and female or female on both sides. The unit is designed with custom made distributed capacitor dielectrics for the inner conductor and a serrated outer dielectric (black material) made from 6/6 Nylon railway approved material. The serration provides a barrier to voltage breakdown that may be caused by contamination from hostile environments that may be found in tunnels.