This is Lego part #44567a 1x2 Hinge Plate Locking with 1 Finger on Side with Bottom Groove in Green
This part in this color is considered a rare part. Rare parts are any parts that are high in value due to being in very few sets, old sets, rare colors, limited quantities, or just due to being high in demand. They are similar but not as difficult to find as Non-Production parts.
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