The TRX triceps extension works your triceps.
TRX Triceps Extension Form Cue
Face away from the base point, with your arms straightened in front or you. Think about bringing your entire body into a plank position, so you’re in one straight line as you bend your elbows, which will bring your forehead and hands together. Keep your elbows pointing forward. Extend your arms (squeezing your triceps) as you push your body into a full upright position. Carefully lower back down to repeat.