Zelus ' ankle weights adding extra resistance to boost core strength and support muscles for faster, more effective results in your daily workout. Maximize Your Workouts: Zelus ' ankle weights fit ankle sizes between6" and 11/ 7" and 12"/6.5" and 11.5/ 7.5" and 12.5", adding extra resistance to boost core strength and support muscles for faster, more effective results in your daily workout.