COASTAL HERM SPRENGER LINK 2.25MM About this item 12" Safe and effective dog training tool with proper use. Weight: 0.2lbs. Dimensions: 3.5"L x 3.5"W x 1.5"H Sprenger Ultra-Plus Prong Dog Training Collar is safe, practical and easy to use. The collar around your dog's neck easier and safer. contains nickel, so will not do for nickel-reactive dogs