Technical features:
* Item: 250S, 250R, 250L, 250XL
* Power: 2.5X
* Working distance: 340mm(S),420mm(R),500mm(L),550mm(XL)
* Depth of view: 80mm (S); 90mm (R); 110mm (L); 120mm(XL)
* Field of View: 90mm (S); 100mm (R); 110mm (L); 120mm(XL)
* Weight 42g
* Frames Ni-alloy or Titanium