Two 1951 banknotes, in very good condition - probably uncirculated though I'm no expert.
No idea why late father in-law had them, they were mixed in with his stamp collection !!!
for fun here is the AI blurb...
The product is a pair of 1951 Bulgarian Banknotes featuring a denomination of 50 Leva. These banknotes are likely to be in uncirculated condition, making them a valuable addition to any collection focused on European currency. With their rarity and historical significance, these banknotes offer a glimpse into the economic landscape of Bulgaria in the mid-20th century, making them a unique and sought-after piece for collectors.