23 sided prism for angle calibration

{"cid":"91223678","title":"23-Sided Glass Prism for Optical Experiments & Angle Calibration","imgUrl":"https:\/\/img.silkroadsl.com\/nimg\/e6\/7d\/5bf65daa5d7c2468c5058a666c98-200x200-1.jpg","attrs":{"Price":"3000~5000 USD","Brand Name":"SPR-ing","Minimum Order Quantity":"1 piece","Delivery Time":"1~3 weeks","Place of Origin":"Shenzhen","Payment Terms":"L\/C,T\/T","Supply Ability":"500\/month","Packaging Details":"Carton","Refractive Index":"1.5","Application":"Optical Experiments","Prism thickness":"17-20mm","Material":"Glass","Flatness of working face":"Grade 0 (Grade II): \u2264 0.03um","Excircle diameter":"\u03c6 80-\u03c6 150mm","Rotating center aperture":"\u03c625mm","Surface roughness of datum plane":"Ra \u2264 0.05 um"}}