keplerian prism loupes 3.5x has sharp image, it is a little heavier, than Galilean style Items: 350KS, 350KR, 350KL, 350KXL Power: 3.0X Working distance: 340mm(S),420mm(R), 500mm(L),550mm(XL Depth of view: 45mm (S); 45mm (R); 45mm (L); 45mm(XL) Field of view: 55mm (S); 60mm (R); 65mm (L); 70mm(XL)L) Weight: 78g Frames: Ni-alloy or Titanium 4x magnification uses a prism system, which offers very clear image. Camber hinge offers comfortable view angle. Prism system give you a wider field of view with maximum magnification Items: 400S, 400R, 400L, 400XL Power: 4.0X Working distance: 340mm(S),420mm(R), 500mm(L),550mm(XL Depth of view: 40mm (S); 40mm (R); 40mm (L); 40mm(XL) Field of view: 50mm (S); 55mm (R); 60mm (L); 70mm(XL) Weight: 80.5g Frames: Ni-alloy or Titanium 5x is also base on the prism system and provides more magnification than 4.0x while using the benefit of prism system Items: 500S, 500R, 500L, 500XL Power: 5.0X Working distance: 340mm(S),420mm(R), 500mm(L),550mm(XL Depth of view: 35mm (S); 35mm (R); 35mm (L); 35mm(XL) Field of view: 40mm (S); 45mm (R); 50mm (L); 60mm(XL) Weight: 84g Frames: Ni-alloy or Titanium 6x has the largest magnification in the series of our products. Comparing with other products in the market, it combines the largest magnification and light weight, users can enjoy their work with great accuracy while filed of view is preserved Items: 600S, 600R, 600L, 600XL Power: 6.0X Working distance: 340mm(S),420mm(R), 500mm(L),550mm(XL Depth of view: 25mm (S); 25mm (R); 25mm (L); 25mm(XL) Field of view: 40mm (S); 45mm (R); 50mm (L); 55mm(XL) Weight: 84.5g Frames: Ni-alloy or Titanium