... , ±8D, ±10D, ±15D, ±20D.5. Aperture wheel: red-free filter, Large spot, small spot, hemispot.Technical Specification:Name of aperture Dimension ... , ±3D, ±4D, ±6D, ±8D, ±10D, ±15D, ±20DAperture: red-free filter, Large spot, small spot, hemispotRated voltage: AA alkaline or Ni-MH ...