Our Herm. Sprenger® Ultra-Plus Prong Dog Training Collar is safe, practical and easy to use. This training collar features a solid fastener plate that provides a more secure connection making fastening the collar around your dog's neck easier and safer. To adjust size, add or remove individual links. The patented center plate construction and symmetrical prong placement provide natural contact for optimal communication. Available in 2.25mm x 12", 3.0mm x 16", 3.25mm x 18" and 3.8mm x 20". Herm. Sprenger® offers a variety of high-quality, specialty chain products.