Coastal Pet Products DCP554020 Titan X-Heavy Chain Dog Training Choke/Collar with 4mm Link, 20-Inch, Chrome Titan dog training choke/collar is excellent for gentle control This extra heavy quality chain is argon welded and chrome plated for maximum strength and durability It will not tarnish, rust, or break and recommended for professional training Use only when dog is attended on leash and is sized by total length, including the rings Measures 20-inch overall length and 4.0-mm link diameter