This boneless cut is from the Sirloin primal on outside of the beast. This roast is often cut across the grain into steaks, which may again be cut into thirds for food service use. While not as tender as cuts from the Short Loin, these are sufficiently tender to support cutting steaks reasonably thick.
The photo specimen is a steak 11 inches long, 5 inches across and 1-1/8 inches thick, weighing 1 pound 13 ounces.This would be #1184 from loin cut #184.
There is also a cut #184B "cap off". The cap is that portion to the upper left, and is usually removed by professional meat cutters because it is loose and the grain goes in a different direction. It is separately cut into #1184D Top Sirloin Cap Steaks.
More on Cuts of Beef.