T-50 is the width. I just re-covered my seat had some problems, but figured out as long as I put the spot I'm stapling on a hard surface, used one hand to hold the stapler firm against it, and squeezed with the other hand, it would keep it from jumping when the staple popped. And since I haven't grown that third arm yet, I used those locking pliers (with cardboard on the visible surfaces) to hold the vinyl in place while stapling. Holding the stapler firm while stapling is key to solid penetration. If it hops the staple won't go flush. I don't know the exact length staples I used, but I used the shortest T-50 I could find so they wouldn't poke thru. I'm going to guess 1/4", but I can't confirm till I get home and check the box. Hope this helps save some time and postage. :knucks: