L-sit pull up (wide towel grip) ("Pull ups" Latissimus dorsi/biceps strengthening, towel grip (wide), L-sit position)

Stand beneath a pull up bar.
Lay a towel across the horizontal handles so that it hangs down evenly at each side.
Hold onto each end of the towel and hang from your arms.
Pull your shoulder blades back and down.
When ready, pull down and back through both arms evenly and ascend throughout the full range of motion.
Control your return to the start position, and repeat.
Try to avoid generating momentum from your legs throughout this exercise