That looks like the snap in for the T610/T615/T637, which I have. I'd take a photo of it with the phone in it but the X is at the body shop. (Wife bumped someone.) The reason I wonder about the snap in the power connector. Looks like two separate conneectors with a divider in the middle. This is the newewr desktop stand for it, the photo is tough to see.
http://www.sonyericsson.com/images/s...500_0_4000.jpg
Where as the 810 has no divider. Here's a flash for the 810.
http://www.sonyericsson.com/images/s...500_0_4000.jpg