TimeSpan.ParseExact with Milliseconds

I am trying to parse a string into a timespan format of minutes:seconds:milliseconds. So 00:00:02 I would expect 2 milliseconds. But it is parsing as 20.

const string tmp = "00:00:02";
var t1 = TimeSpan.Parse(tmp);

// minutes: seconds: milliseconds
var t2 = TimeSpan.ParseExact(tmp, @"m\:s\:ff", System.Globalization.CultureInfo.InvariantCulture);

Why is milliseconds 20 and not 2?