STRENX

Strenx by GymWatch is a wearable fitness tracker that tracks all movements of your upper and lower body. So you can wear it on your arm or leg. When you will do upper body workout like pull up. push up or dumbbell, barbell, bench press exercise it will detect your straight for how much you are capable for that particulate weights and the perfection of your reps. All you can monitor by your mobile app and adjust weights so that you can do the reps properly.
Same way you can wear on your leg when you will do workout for quads, hamstrings or for Calves. App supports both iPhone and android device. Strenx is available in eBay and amazon price $50 to $65.