... The neat thing is they come in these book like sleeves with a clear front with proof covers of many of the classical record being released. Dozen+ Sleeves front and back. Almost like a record sleeve slick, but not quite. It states that they are proofs....
I am not familiar with these Masterworks in particular, but other labels have offered either promo sampler LPs or press kits with reproductions of the featured albums' cover slicks -- notably Capitol/Angel and Elektra.
Are any of these issues in the Masterworks "Sound of Genius" (SOG) series or the Audition Quarterly Sound Magazine series?