Photograph of radio equipment, Atwater Kent Radio, Southern California, 1927. "Cunningham Radio Tu[bes], Les[ilg]e" -- signage on window. "USL, Reg[istered] U[nited] S[tates] Pat[ent] Off[ice]; +45, + 22 1/2, No. 486, For best results put in service before Jan1928" -- embossed on battery. "Battery [ilg] Ray Thomas Inc[orporated], Voice Tested [ilg]" -- written on amplifier tube. "Cunningham Radio Tubes, Since 1915- Standard for All Sets, Type CX-301-A, Amplifier, Fil Volts-5, Fil Amp-25, Plate Volts-125, Maximum, E. J. Cunningham Inc[orporated], New York, Chicago, San Francisco, Amplifier Tube" -- written on boxes. "For use with sets of 4 or more tubes, Eveready, This battery may be used in any position, Date Sold, No. 486; Eveready Radio 'C' Battery, National Carbon Co. Inc[orporated]" -- written on batteries.