Features: 1) CR-39 progressive short corridor (14mm) 2) Diameter: 72mm, 75mm 3) Good for small Features: 1) CR-39 progressive short corridor (14mm) 2) Diameter: 72mm, 75mm3) Good for small and medium size frames4) Base: 2.00B, 4.00B, 6.00B, 8.00B5) Central thickness: 8.5 ~ 10.0mm