These will challenge you more than any dumbbell row. You'll be essentially rowing your bodyweight with one arm.
Don't let your shoulder shrug up, keep your core braced, and pull with control. You'll feel your core work double-time to stabilize the offset load. Your pulling muscles will also contract deeply. To make it easier, simply go flat footed or adjust your angle.
You multitaskers out there will love this movement as it allows you to work the rectus abdominis, the obliques, and the serratus at the same time. Too bad the rest of your life isn't as efficient.