The porterhouse was always called a T-bone in the past. It's the thicker end of the loin where it meets the tenderloin. as you move away from the tenderloin, the T-bone is mostly just striploin. We bone everything out as I'm always saying you can't eat bone and it just takes up room in the freezer. So boned out, the porterhouse, (T-bone) turns into the tenderloin and loin steak packaged separately. If you buy T-bone steaks, look for the ones with the largest piece of tenderloin on the smaller side of the bone.