Sphere powers range: +16.75D to -19.00D,with minimum reading 0.25D or 0.12D (when+0.12D auxiliary lens or optional ?.12D lens in use) +26.75D to -29.00D (when optional ?0.00D lens is in use) Cylinder power range: 0 to ?.00D,with minimum reading 0.25D or 0.12D (when auxiliary lens is in use) 0 to ?.00D (when ?.00D auxiliary lens is in use) Astigmatic axis scale: 0 to 180?in 5?steps Cross cylinder: ?.25D,reversal type (synchronized with astigmatic axis) ?.50D optional Rotary prism: 0 to 20ΔD in 1ΔD step