We think these were probably used to make a 25mm focal length Huygenian eyepiece. The box is marked, Plummer Turret C Lenses 7507-4170. There is a plano-convex lens that is 16mm in diameter by 20mm focal length. The center thickness is 3mm and the edge thickness is 2mm. The second element is a double convex lens that is 16mm in diameter by 100mm focal length. The center thickness is 3.5mm and the edge thickness is 3.15mm. Both have pinkish/purple anti-reflective coatings.