Plano-convex objective lens mounted in a cardboard ring. The edge is covered with leather. The aperture is 84 mm, the focal length 6,050 mm, and the ring diameter 115 mm. The glass, which has a red tint, contains elliptical bubbles and some inclusions. One side of the ring is inscribed "Vangelista Torricelli. Fiorenza 1646 Braccia 10.1/4" (5,970 mm).