3x4x.75" deep box contains heavy metal premium 2.25" long and .5" thick. This comes w/either brass or aluminum case and this version is brass. Derby Foods Inc., 1949. Original owner added name to the mailing label, but otherwise box is Mint. Premium is designed w/owner's personalized serial number at upper right "118013." Top surface features decoding wheel plus opening to serve as a magnifying glass. Right side edge has opening w/internal red wheel which can be used to ink stamp individual alphabet letters. One side edge has images of Sky King's plane "Flying Arrow" and his horse "Yellow Fury" while opposite side edge serves as a ruler. Underside of piece has full figure of Sky King w/his initials stamped along side. One of the most complex decoders of all time and extremely well made. Luster has some tiny 1/16" circular marks but remains brilliant and NM. 4x6" instructions are bit tanned with small creases and edge tears from being boxed. Rarely offered complete.