3-IN-1 SINGLE RUCK WEIGHT: Featuring US Design Patented design with a circular 2-inch hole at the center, 20 LB ruck weight easily connects to Olympic barbell for versatility; Use it as a rucking weight, kettlebell, or plate for various exercises ROUNDED EDGE PROTECTION: The US Utility Patent Pending smooth-edge design of rucking weights protect your floors & minimize scratches on surrounding equipment, so you can train without worry