The semi virgin PSF covers a denier from 0.8D, to 1.5D, 3D, 6D, 7D, 15D, regular solid is made for fine denier of 0.8D to 3D, hollow conjugate is made usually for denier from 3D to 15D, Fiber length could be 38mm, 64mm, special length like 51mm, 76mm etc could be customised if you can meet the MOQ...