Tal Barlow

[Geno]

Just a quick question.

I Have noticed the top part of my 2 x Tal Barlow unscrews to reveal an external thread, what is this for?

I have searched on the forum and cannot seem to find an answer

[nicnac]

i will have a look at mine when i get in but i dont recall being able to remove the top.

Barlow lens 2x, 3x, 4x 1.25 optic sights, night optic sight, devices of night vision, night vision glasses, night field-glasses, laser range finders

[Bizibilder]

Its 30mm OD 0.75mm pitch - Not sure what that would fit as a "standard".