Seller: e-eddie (419) 98.3%, Location: Stanford-le-Hope, Ships to: GB & many other countries, Item: 133247314117 Here are three clock keys with measurements of their apertures approximate. The silver coloured one with a single winder is approximately 4 mm wide, the brass one is 5 mm wide and the two key one is 4 mm and 2 mm wide. Please only bid if you intend to buy. Sorry to have to say this but there are some time and effort wasters out there!!! PLEASE MAKE SURE THAT YOU ARE HAPPY WITH POSTAGE COSTS BEFORE BIDDING. The postage quoted is for Second Class Signed For Mail.