If you are very proficient at double-unders, use this time to work on crossovers, heavy rope or drag rope double-unders.
As Many Rounds and Reps as Possible in 16min of:
400m Run, Row, Ski or 21/18 Assault Bike
20 Alternating Curtsy Squats
20 Russian Twists with plate
20 Hand Plank Plate Taps
20 Goblet Squat with plate
20 Double-unders or Variation