Soviet Union - 1937 Mi. Block 3, expertised by Z.S. Mikulski + L. Hovest - with the Shatylo error 726 PB K1 – a verry RARE piece

Soviet Union 1937
Mi. Block 3 – registred airmail letter from Moskow to Vienna franked with this block, expertised with unlisted plate flaw in Michel cat., but listed in Shatylo Special stamp catalogue 2023 (726 PB K1) – a verry RARE piece.
Description:
Offered is an original 1937 Soviet Union postage stamp, Mi. Block 3, registred airmail letter and expertised by Z.S. Mikulski and L. Hovest.
The certificates were translated with Google Image - Translate, so there might be translation errors (see photo).
Plate flaw: "Light spot on the right "1".
A distinct printing flaw recorded in Shatylo Special stamp catalogue 2023 (but not listed in the Michel Special 2017).
The flaw is visible in the scans.
Condition: Souvenir sheet on letter.
Scarcity: RARE.
Certified: Certificate with photo by Z.S. Mikulski + L. Hovest.
Estimated auction result for this item (Used condition + plate flaw + certificate): €2500, (based on market comparisons for similar early Russian issues with varieties) considering the rarity and specialist interest.
A must-have for advanced collectors.
Certificate and high-resolution images included.

Shipping Details:
• Tracked and insured shipping
• Carriers: DPD / GLS / FedEx / Romanian Post
• Secure packaging
• Non-EU buyers: Import duties/taxes are the buyer’s responsibility.

USA users: please don’t bid. I don’t ship to USA.