Herm Sprenger Stainless Steel round link collars. Also known as the Choke Collar. This top quality training aid used by the pros worldwide. Most common collar for average sized GSD is the 20 inch. These top-of-the-line chains won't dull, rust or discolor your dogs fur under any conditions and they're the strongest available. Available in Fine ( 2mm) and Medium (3mm) links.

Sizes:

Fine Link - 2mm from 12" to 26"

Medium Link - 3mm from 16" to 26"

Large Link - 4mm from 20" to 26"