This arm twister trainer targets biceps, triceps, chest, shoulders, and forearms with adjustable resistance from 30 to 120 pounds. Two sets of spring bars (4 total) combine to create four resistance levels, progressing from warm-up exercises to advanced muscle building. Leather-wrapped springs protect against pinch injuries and prevent rust for long-lasting durability. The detachable design breaks down easily for storage or travel to the gym, office, or on trips. Includes an illustrated poster showing proper form and technique for each exercise. Suitable for men and women looking to build upper body strength without bulky equipment. Note: users 5'7" and taller can perform all inner handle exercises.