Although this looks a little bit more involved, it really isn't. It's the same thing again and again. Same as above. This is the heading of the form item. It denotes how the results of the reader will arrive at your e-mail box.
SIZE denotes the size of the box.
Try putting two there if you'd like to see what it does. I prefer just one. More than one item tends to defeat the purpose of the Pop-Up Box. People write and ask if it's possible to make the above pop-up box a series of links for people to choose and then go to. With HTML alone, it isn't possible.