This item will cover the cost to convert an existing Custom Coaxial Needle from Style A to Style B. You will need to let us know what Dimension E should be. See this worksheet: http://www.ramehart.com/pdf/coaxial_worksheet.pdf The default value is 25mm. If you need a different value, enter it in the comments box or on a note with the Custom Coaxial Needle that you are returning to us for retrofitting.