Twister Arm Trainer for Upper Body Workout, Adjustable Spring Resistance (40-100lb) for Triceps and Forearm Training 1.Full-Body Muscle Engagement Technology: This professional-grade twister arm trainer activates 6+ major muscle groups simultaneously through its U-shaped dynamic resistance system. Engineered for chest expansion, arm sculpting, back strengthening, and grip conditioning - ideal for compound functional training with 300% higher muscle activation than traditional spring bars 2.Spring System: Features triple-reinforced chromium steel springs with 50,000+ cycle durability tested, delivering smooth 40-100lb progressive resistance. Anti-corrosion coating maintains consistent elasticity while noise-dampening tech ensures quiet home workouts 3.3D Ergonomic Safety Design: Patent-pending angled torsion bar with medical-grade silicone grips (9.8' circumference) prevents wrist strain. Memory foam palm cushions with sweat-wicking texture provide secure hold during high-intensity sessions 4.Smart Progressive Training System: Modular design allows instant resistance adjustment through detachable spring units - combine 2/4 springs for 3 difficulty modes (Beginner 40lb, Intermediate 70lb, Advanced 100lb). Includes digital workout guide with 25+ professional routines for muscle growth/fat burning