The present invention is directed to a new foamed elastomer composition including elastomer, hollow fillers, and reinforced fillers for supporting the conducting wires in the test probes for wafer level testing and burn in and interposer connector applications. The thermally stable elastomer resin is mixed with hollow fillers and reinforced fillers before filling into the probe or connector mold with an array of elongated conducting wires, then is crosslinked by a crosslinking agent and a catalyst. The use of compressible hollow fillers to foam the elastomer has been successful to enhance the compliance and resilience, and to reduce the thermal expansion, density, and dielectric constant of the elastomer.