Brass ring with silver plating. <table border="0"> <tbody> <tr> <td><strong>     SIZE </strong></td> <td><strong>     DIAMETER </strong></td> </tr> <tr> <td>S</td> <td>17,5mm</td> </tr> <tr> <td>M</td> <td>18mm</td> </tr> <tr> <td>L</td> <td>19mm</td> </tr> <tr> <td>XL</td> <td>20mm</td> </tr> </tbody> </table>