Spring material for coaxial RF switch

i want to design the coaxial rf switch ,but now not know use which spring,
if anyone know,please tell me ,thanks

As for the spring material, beryllium copper is the best.
What kind of frequency are you trying.
And what is the power level?
Regards,

want to buy the springs used in rf switch, the switch time is 20 millisecond maximum, the life is 5,000,000, cycles. the work temperature is
-55℃--85℃. the spring's shape is common column.if you can offer the spring ,i would thank you very much.