Wonder Arms Arm Exerciser Wonder Arms is the training device that helps you get rid of those problem areas under your arms. Get incredible results with unique dynamic resistance moves that work your back, biceps, triceps, shoulders, and even your chest all at once. You'll feel your muscles tone and tighten while burning calories without straining your joints. Perfect for all fitness levels. It targets four different muscle groups and comes with three different resistance bands. What is Wonder Arms? Wonder Arms is an ergonomic training device that works with resistance. Choose the resistance band depending on your level (beginner, intermediate, or experienced) and place it on Wonder Arms. Depending on where you place the device, you can train your shoulders, biceps, triceps, chest, and back muscles. The exercises are easy on your joints and can be done both sitting and standing. Wonder Arms targets these areas and transforms them into firm, toned arms and shoulders you'll be proud to show off.