A threshold is at an exterior door to stop weather penetration. A saddle is at an interior door to provide a larger door undercut for area rug clearance. A strip between two flooring materials is called a reducer strip wherever it occurs. The number of possibilities for the location and the difference between the two materials makes the question impossible to answer without making wild guesses

I'm the OP. Those marble strips are nice but they only come in white. Since our floor is dark they wouldn't work for us. We ended up going with wood. There was no molding of the right shape or height, especially since we were trying to bridge a height transition: the tile being higher. We bought ranch molding that was designed for window and door frames. If you are not familiar with ranch molding, in profile it has a slope: one side is high and the other side is lower. The installers has to shave some wood off the back to make it fit (to reduce the height), but that was their problem since they had promised they would come up with something nice for us and had not. We had them bring the wood right before the weekend and then we stained and varnished it to match our other moldings. On Monday they came back and installed it. The carpeting is a berber, and the edge is tucked lightly under the lowest edge. The high side butts against the tile/durock and a small caulk line is in between.

Is your carpet and tile a gray color? I ask because I see your only color choices are aluminum or brass. Also, will there be a height difference between carpet and tile? If I had to choose I'd go with the Schiene since the Reno has a raised/angled edge. We had a similar problem where travertine met hardwood so we had a transition piece milled locally (couldn't find the correct ht premade) and then had BM custom match a stain to the travertine. Just throwing out other options! I would talk first to your carpet installer and ask how well they can finish the edges. Here is a link that might be useful: Profiles This post was edited by annz on Mon, Dec 10, 12 at 16:48

You've had a Schluter edge put on a tile that needed a proper CARPET REDUCER. A REDUCER is just that. It REDUCES the height of the tile DOWN TO the height of the carpet. That's why they are called reducers. They are wedge-looking pieces that make this a non-issue. Your carpet/pad combination is not thick enough to handle the "L" you have. You will need to have a reducer added. It won't be pretty. The schluter "L" has been installed at the same time as the tile...which means it is sitting UNDERNEATH the tile. It will take some effort to change this. A decent tiler will handle this without much issue. Whomsoever made the original decision will pay for the change. That's how these types of change orders work in new builds. The reducer install will be much cheaper than removing the carpet and replacing the pad and then reinstalling it all.