These Polarising Filters from Oculus are used to separate visual impressions of both eyes during refraction. This product is for use only with Oculus universal measuring glasses UB6, UB4, UB4 height adjustable, UB3+ and practice glasses. 
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To use, simply insert the polarising filters with "R" in front of the right eye and "L" in front of of the left eye. Each filter should be inserted into the lens holder closest to the eye. 
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The filters come with two disposable cleaning swabs which should be slightly wetted with isopropanol or spirit to clean. 
 
please not these filters use CIRCULAR POLARISATION not LINEAR