It is plane glass plates designed to test the flatness and parallelismof measuring surfaces of the interference method.Without boxMeasurement range of micrometers - 25-50mmComes with calibration certificate in original plastic case.Diameter - 30 mmHeight - 40.62,40.50,40.75,40.87Other sets can have different values (nearly these) height.Parameters:The deviation from the mutual parallel measuring planes - 0,0006 mmNonflatness measuring planes-±0,0001 mm Normal 0 false false false RU X-NONE X-NONE MicrosoftInternetExplorer4 If you have any questions aboutthis product, please tell me, I will give all the necessary information.If you need moreother tools, tell me, I will do my best to find the tools you need, and willset it for you at eCRATER. ABOUT FEEDBACK:Please, leave your Feedback onthe receipt of the goods. For me it is very important to have feedback from mycustomers. If you have any questions about an item, PLEASE CONTACT withme, I always try to achieve the satisfaction of my clients so that You wouldhave to deal with me in the future.NOTE ABOUT DELIVERY TIMEI try to send the goods you paid during the business -day. Delivery time depends on the carrier.