Our Herm. Sprenger® Extra Links for Dog Prong Collars may be added or removed for the proper fit. Available in a pack of three and in fine, medium, 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.