Convert TimeSpan to/from string

I never remember what to type in config file

 TimeSpanConverter tsc = new TimeSpanConverter();
TimeSpan ts = new TimeSpan( 1, 2, 3, 4, 5 ); // 1 day 2 hours 3 minutes 4 seconds 5 millisec
string s = tsc.ConvertToInvariantString( ts ); // 1.02:03:04.0050000
ts = (TimeSpan) tsc.ConvertFromInvariantString( s );
Console.WriteLine( s );

So this is the code.