Fantastic, absolutely awesome hardware. Excellent quality. Needed a push-open pop up drain to fit my Duravit sink (Starck 2 washbasin) and this is perfect. I really do wish it came with installation instructions, but in spite of that fact and our being plumbing-phobic, we managed to get it installed very successfully with a little common sense. It does work a little differently than most American drains in that there's no metal tube that passes through the drain hole from top to bottom of the sink. There really is a gap where just the screw lives. But that's also where the overflow water enters the drain. So yes, this is indeed for an overflow sink. And yes, it does come with a 1-1/4" extension pipe that attaches at the bottom of the drain. Just attach your P-trap to it.To install you will need a 4mm Allen wrench. If you're buying one for this job I'd get a T-handled wrench so you'll have enough of both leverage and reach.The finish on these parts is stunning and the pop up action is lovely. Highly recommend for Duravit sinks.