You have an EARLY pressing, NOT a first pressing.
1D / 1AD
SD-1 1D indicates this side was pressed from one of the first 4 pressing stampers sent to Columbia record plants
SD-2 1AD indicates this side was pressed from a MUCH LATER pressing stamper sent to Columbia record plants
Given the matrix information and difference between the 2 sides, I would suspect that your side 1 was pressed near the end of the useful life of this stamper and probably does not sound as good as true first pressing.
A first pressing of KOB would have matrix information for both sides showing some combination of 1A 1B 1C 1D....no higher.
1E or 1F represents an early repressing of this title.
Columbia LPs of the period DID use thin clear sealed inner sleeves as described. I have purchased several first and early pressing Columbia titles from this period with sealed inner sleeves.
These sleeves were not air tight, and the gauge of the material was very thin. It is possible for mold spores to have settled on the LP surface, even though the inner sleeve is "sealed".
Value ? Whatever someone would pay. List it on EBAY with large clear pictures of the SEALED inner sleeve. Last 2 SEALED inner sleeve copies sold for $400+
https://gripsweat.com/search/?query=sealed+kind+of+blue+1355&button=
1D / 1AD
SD-1 1D indicates this side was pressed from one of the first 4 pressing stampers sent to Columbia record plants
SD-2 1AD indicates this side was pressed from a MUCH LATER pressing stamper sent to Columbia record plants
Given the matrix information and difference between the 2 sides, I would suspect that your side 1 was pressed near the end of the useful life of this stamper and probably does not sound as good as true first pressing.
A first pressing of KOB would have matrix information for both sides showing some combination of 1A 1B 1C 1D....no higher.
1E or 1F represents an early repressing of this title.
Columbia LPs of the period DID use thin clear sealed inner sleeves as described. I have purchased several first and early pressing Columbia titles from this period with sealed inner sleeves.
These sleeves were not air tight, and the gauge of the material was very thin. It is possible for mold spores to have settled on the LP surface, even though the inner sleeve is "sealed".
Value ? Whatever someone would pay. List it on EBAY with large clear pictures of the SEALED inner sleeve. Last 2 SEALED inner sleeve copies sold for $400+
https://gripsweat.com/search/?query=sealed+kind+of+blue+1355&button=