Check the listing for details. Rare Vintage Cosmorule Series 1A - Double Sided Slide Rule Conversion Chart. Condition: Used. Listed at 15.19 USD. This is a vintage Cosmorule series 1A. It is a double sided slide rule conversion chart and comes with original instructions. Please look at the photographs for condition. If you have any questions please ask. Please also look at the other items I am selling. I aim to add new listings most days. If you are interested in more than one item I will combine postage wherever possible. If I have excluded your postal location and you are interested in an item please message me for a postage quote. PLEASE NOTE: It is against e-bay policy to give out contact details before a sale has been agreed. Even responding to such a request can result in e-bay stopping me from trading and closing my account. So, please don't ask! Thank you.