Click the Duration field, and type 400. Avoid the temptation to press Enter or Return, as
this will close the panel. Premiere Pro automatically adds punctuation, turning this into
00:00:04:00 (four seconds) as soon as you click away or press the Tab key to move to the
next field.
Click in the Name box, and type a comment, such as Replace this shot.
Click OK.
The marker now has a duration on the Timeline. Zoom in to the Timeline a little, and you’ll
see the text you typed into the Name field.