Description Choosing which Duplex Insert is right for you: There are two main indicators for the diameter of the ring : Distance Eye to Iris-Aperture And Length of Lenshood II That’s all you need. If you have Rear-sight Spy, you will need a diameter between 3,8 and 4,2 with a distance eye to Iris aperture of 4 cm to 5 cm Feinwerkbau rear-sight, you need a long Lenshood II, there are 4,3 – 4,8 Anschütz 7000er rear-sight also with long lenshood II it´s similar to Feinwerkbau. The length of the sightline or Diameter of the front-sight tunnel does not matter.
