Adjustable C Clamps. Pair of nipple clamps connected by 12" of chain. The 1" long thumbscrews are fine-threaded for precise adjustment of pressure. The thumbscrews cannot fall out even when the clamps are fully loosened. The "grabbing" surface is approx 3/4" long by 1/4" wide. This is good-ol' kinky ingenuity in cold hard metal. You may remove the chain with pliers easily if you desire.