Eyepiece lens mounted in a cardboard ring. Its diameter is about 33 mm, its exposed diameter 25 mm, and the diameter of its concave polished part 23 mm. Its focal length is ‑64 mm (the negative focal length means that the lens is diverging). The glass is clear and contains a number of aligned elliptical bubbles. On one side of the ring the number 3 3/4 is legible, and presumably this means that this ocular was to be combined with an objective of 3 1/4 braccia (1,900 mm) focal length. This lens is similar to lenses inv. 2585 and inv. 2584. Its origin is Florentine, and it should be dated to the period 1640-1660.