The standard version with two rings. Equipped with center-plate and assembly chain, it is a classic option for dog training. Herm Sprenger is one of the leading manufacturers of dog training products, best-known for their quality, reliability, and safety. All products are made in Germany, utilizing only the finest materials and components. Through their continuous quality control efforts over the past 140 years, Herm Sprenger’s training collars are recognized as one of the best training collars sold on the market today. Sizes Available: * Gauge 2.25mm x 16" (41cm) - fits up to a 13" neck measurement * Gauge 3mm x 22" (55cm) - fits up to a 18" neck measurement * Gauge 3.2mm x 23" (58cm) - fits up to a 19" neck measurement * Gauge 4mm x 25" (63cm) - fits up to a 21" neck measurement If your dog exceeds the starting length capacity of the suggested wire gauge size, you will need to purchase additional middle links (sold separately).