Is this thing a fuse?

Is this thing a fuse? If so, what are the differences with other kind of fuses? If not, what it is?

<a href="http://s54.photobucket.com/albums/g81/Dothang67/mustang%2067/?action=view&current=IMG_1672.jpg" target="_blank"><img src="http://i54.photobucket.com/albums/g81/Dothang67/mustang%2067/IMG_1672.jpg" border="0" alt="30A fuse"></a>

<a href="http://s54.photobucket.com/albums/g81/Dothang67/mustang%2067/?action=view&current=IMG_1673.jpg" target="_blank"><img src="http://i54.photobucket.com/albums/g81/Dothang67/mustang%2067/IMG_1673.jpg" border="0" alt="30A fuse back"></a>

Thanks!