Sliding floor pulldown

Lie face down with your arms extended overhead and your hands on a surface that can slide smoothly.
Press your hands into the floor and pull your elbows down toward your sides, sliding your upper body forward.
Extend your arms overhead again under control and repeat.

Tips

As you pull your elbows toward your sides, think of driving your hands straight back along the floor rather than lifting them, so the sliding surface stays in contact throughout the pull.
Keep your hips and lower body in contact with the floor throughout the movement so that the forward slide comes from your upper body being pulled by the arm action, not from pushing with your legs.
When returning to the start, extend your arms overhead at a controlled pace rather than letting them drop forward passively, so you maintain tension through the full repetition.

Shrugging the shoulders up toward the ears at the start of the pull instead of keeping them drawn away from the ears as the elbows move down and back.
Bending the elbows sharply and pulling with the arms alone rather than initiating the movement by driving the hands back into the floor, which reduces the range through which the lats are working.