GMORS O-Ring Master is the completed tool for standard rubber seal sizes. When you use this APP, you do not need to have internet. In addition to O-Ring sizes, it also includes the search functions of X-Ring and Back-Up Ring. You can also use O-Ring Housing to choose suitable O-Ring in your application. Main functions are as follows: Dimension Search: O-Ring, X-Ring and Back-Up Ring. - MM and Inch are both available. - Full standard O-Ring series: AS568, METRIC, JIS B2401 P / G / S / V, JASO F