| Description | Universal Trial Frame, black, light-weight metal / plastic, for 5 pair of lenses, independent right and left adjustment of PD 1.9" - 3.15" / 48 - 80 mm. Bridge height and inclination operates by a rack and pinion. With vertex distance scale. Sides | The trial frame is one of the tools of the trade for every refraction professional. Subjective lens determination requires craftsmanship and manual skill. Your professional competence will be perfectly demonstrated with the new Universal Trial Frame |