  We present Silver-epoxy filters combining excellent microwave attenuation
with efficient wire thermalization, suitable for low temperature quantum
transport experiments. Upon minimizing parasitic capacitances, the attenuation
reaches >100 dB above ~150 MHz and - when capacitors are added - already above
~30 MHz. We measure the device electron temperature with a GaAs quantum dot and
demonstrate excellent filter performance. Upon improving the sample holder and
adding a second filtering stage, we obtain electron temperatures as low as 7.5
+/- 0.2 mK in metallic Coulomb blockade thermometers.
