I have acquired a Model 504 power meter by Cooper Lasersonics.

It came with three attenuators, for 10W, 1 and 3W, 100 and 300mW. The range switch, however, goes down to 10 and 30mW. Should there be another front cone for the bottom range, or is the sensor used bare ? I'd have thought there would at least be an entry cone even if it had no attenuator disc.