These black-painted iron quick links feature an antirust coating for durability. Designed for easy use, simply twist clockwise to open and anti-clockwise to close, with smooth threads ensuring effortless installation and removal. The M4 chain link is versatile, ideal for lighting chains, keychains, camping, pets, hiking, fishing, backpacks, and ropes. (Not for climbing or high-altitude activities.) With a 100 lb max load, always use within capacity for safety. Compact at 1.7" x 0.78" x 0.15", ensure the connecting hole diameter is over 7mm/0.4".