Dare you to say that fast when you've had a drink or two. It's used for placing your stamps perfectly on your paper but if you still have no idea what it is used for check out this video link HERE.
For me personally I normally use it for adding my sentiment - I'm sure I'm not alone & do this last & don't you hate it after expending all that time & effort - it's crooked, so if you don't own one I'd really recommend getting one. A one off investment of $26.95 which will be quickly repaid.
One of the cool tips I heard at convention was rather than stamping on the image sheet (which does get messy as it takes the ink awhile to dry) use a new square of vellum card stock for each stamp set & have your words etc already stamped ready to go in the set - makes it much quicker, easier & cleaner. A pack of 20 sheets of A4 vellum card stock costs $14.95.
Anyone ordering the 2 of these items together I will discount 10% if you mention reading this post ie. $41.90 reduced to $37.70 (shipping costs to be added still).