The pitches marked on the forks are,
which are not the usual pitches used in music. The label on the box doesn't help much by way of an explanation of the difference.
The notes indicate that it is a diatonic scale and the proportions (fork pitch/C256) are as follows,
indicating a Ptolemaic diatonic scale. One may ask, "Why is this particular scale is used?" It presented a bit of a puzzle and further study was indicated.
I consulted Rayleigh's The Theory of Sound and found the C256 "is usually adopted by physicists and acoustical instrument makers, and has the advantage of simplicity." But he says nothing of its origin. Helmholtz in On the Sensations of Tone is not much more helpful. He does refer to "The theorectical English pitch, c' = 256" which indicates an English origin. Through a Google book search I came across Ellis' History of Musical Pitch which mentions C512 and a report by the Society of Arts. Another book search led to an entry in the Journal of the Society of Arts, Jun 10, 1859 which discusses the need for a "uniform pitch or diapason." C512 was favored by Mr. Hullah. The signatures there indicate that members of the Royal Society were present. One also get the impression the C512 scale predates this discussion. A paper, The origin of the tuning fork, that I found at the National Institutes of Health indicates that John Shore and Handel used this scale.
So this may be a partial explanation for why this particular scale is used by the scientific community.