NWOT-SPRI Thumblock Wrist Weights. 2 - 2lb weights = 4lbs. Resistance & Cardio Product Key Details 1. No-Slide Design: These weights utilize an integrated thumb loop that prevents them from sliding down or shifting around your arms while running or exercising. 2. Fitness Benefits: They are commonly used during walking, jogging, aerobics, or shadowboxing to increase calorie burn and gently build muscular endurance.