# Characteristics of some alternative fibers

Although the Madge Smart 16/4 Fiber Ringnodes are optimized for use with 62.5/125um fiber, you can use other fibers.

The characteristics of some alternative fibers are:

| Alternative fibers
Core diameter Cladding diameter | 50um 125um | 85um 125um | 100um 140um
Nomimal numerical aperture | 0.20 | 0.26 | 0.29
Core/cladding concentricity error | <=6% | <=6% | <=6%
Core non-circulatory | <=6% | <=6% | <=6%
Cladding non-circulatory | <=2% | <=2% | <=2%

If you are using alternative fibers, you will need to check that the Optical Power Budget and Modal Bandwidth are suitable.