"If your goal is to gain strength, develop power, reshape your body or prevent injuries by strengthening the stabilising muscles around your joints - free weight training will be your most effective workout. The Flex Urethane Series from PowerBlock are the fourth generation of PowerBlocks. The urethane coated weight plates offer the ultimate in smooth, quiet performance in addition to their 'flex' technology (patent pending) in both the weight plates and the selector pins making for the most durable PowerBlock yet. The coloured rails are powder coat painted and are on both sides of each block for easy identification of the different weights. With the premium urethane coating, 'flex' technology and the additional weight increments than the Sport Series, this range is perfect for discerning home fitness enthusiast and carries a lifetime home warranty. For Personal Trainers, Sports Coaches and Therapists using PowerBlocks with their clients under fully supervised conditions; the Flex Urethane Series carries a 5-year light commercial warranty."