Coastal's Herm. Sprenger Black Stainless Extra Links for Black Stainless Dog Prong Collars may be added or removed for the proper fit. Available in a pack of three, they come in fine, heavy and extra-heavy gauges. Sophisticated production techniques, consistent quality control, superb craftsmanship and the highest quality raw materials make Herm. Sprenger German chain products superior. Herm. Sprenger offers a variety of high-quality, specialty chain products.