Prism form: Base up,base down,base in,base out Specifications Sphere: 0.0 to -29.50 Diopters, ... ,step:0.25 Prism form: Base up,base down,base in,base out Binocular balance: Rotary prism,polarizing filter and R ... : ±0.25D ,±0.37D ,±0.50D PD: 48 to 80mm in 0.5mm step Retinoscope: +2.00D or+1.50 both ... :90W Package dimensions:590×470×470mmGross weight:15kg Integrated automatic refractometer