Deluxe Adjustable Prong Training Collar with Quick Release, No-Choke Pinch Collar is Safe and Effective, Chrome-Plated for Maximum Strength, Will Not Rust or Break (Sizes: Small, Medium, Large) Deluxe adjustable prong collar is a safe and effective training solution 3.0mm Prong Chrome-plated collar provides maximum strength and durability Smooth and rounded prongs to prevent injury - safe alternative to choke collars Medium: Fits up to 20" neck, for dogs 20 - 40 lbs By Downtown Pet Supply 3.0 mm Prong Chrome-plated collar Fits up to 20&#034; neck, for dogs 20-40 lbs and under Flat tipped No-Choke Pinch Collar Chrome-Plated for Maximum Strength Will Not Rust or Break