Herm Sprenger Stainless Steel Fur Saver Collar Longlink 4mm 21"/54cm EFFECTIVE:  Studies show that 80-85% of dogs stop barking in just one week after using our barking collars, 10-15% of dogs stop within the first two weeks. SAFETY & WARRANTY:  Our anti-bark collar is a humane bark collar with a durable buckle closure that complies with ECA safety requirements. Our no bark collars last a minimum of two years, and we provide a 12 month warranty from the date of purchase. We also provide refunds within 30 days of the purchase date. UNIVERSAL SIZE:  Dog barking collar is suitable for all kinds of dogs: small, medium, large. Lenth is regulated from 5 to 19 inches. FAST CHARGE:  Only 1 hour, and your anti-barking collar is fully charged via USB with your computer, car charger adapter, phone charger, or power bank. 100% WATERPROOF:  No need to take off the anti barking collar on rainy days or while bathing or swimming.