NAVIGATION
Potassium bromide crystal optic disc, 32mm x 3mm, unpolished
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Sodium chloride crystal optic rectangle, 30mm x 15mm x 4mm, unpolished
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Sodium chloride crystal optic rectangle, 38.5mm x 19.5mm x 4mm, unpolished
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Potassium chloride crystal optic rectangle, 30mm x 15mm x 4mm, unpolished
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Potassium chloride crystal optic rectangle, 38.5mm x 19.5mm x 4mm, unpolished
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Potassium chloride crystal optic rectangle, 41mm x 23mm x 6mm, unpolished
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