This is a very early vintage King silver plate curved Bb soprano sax. Although HN White began manufacturing brass instrument in 1893, the production of the saxophone did not begin until about 1916. Thus, the first King saxophone serial number falls in at about 50000, along with King's other brass instruments at that time.
This particular curved soprano sax was manufactured in 1916-1917. It has satin silver plate with burnished engraving. The physical condition is superb! This instrument is (perhaps surprisingly) a very nice playing instrument. It has a well balanced feel and intonation is actually quite good!