Martingale collars are specifically designed to provide more control than a standard collar & (when fitted properly) will prevent your dog from escaping or backing out of their collar due to the cinching function. While martingale collars don't prevent pulling, they are an excellent training tool for teaching your dog good leash manners. They are highly recommended by trainers as the go-to collar choice. Please be sure to follow our "how to measure" guidelines below to ensure you get the perfect fit. The collar size you choose will be the circumference that the collar can adjust when it relaxed around your dog's neck. When tension is applied to the martingale chain it will reduce the collar's size by a max of 4". For example if you choose the 16-20" size and your pup wear's his/her collar at 18", when tension is applied to the chain it can tighten down to approximately 14". Due to the length & thickness of the chain we can't make these style collars any smaller than a 15-19" size range. Constructed with 1" standard beta BioThane® Durable stainless steel chain and screws for long-lasting performance 100% waterproof, anti-microbial, & durable- making them perfect for any adventure from sea to summit Low maintenance & cleaning is a breeze- just wash with soap and water or hose it off, & its ready for the next adventure. Reinforced with heavy duty screws at all stress points to ensure for the strongest hold. We believe screws are the most durable as the threads are tightened & reinforced to ensure your gear will never come apart Adjustable Fit: By including your dog's measurements, we can create a comfortable, secure fit that's just right for them. This is especially helpful if they're between sizes or still growing, so we can make any necessary adjustments to our standard sizing. CUSTOMIZATION DETAILS IF ADDING ON PERSONALIZED NAMEPLATEBy adding a stainless steel nameplate you can personalize your pet's collar with their name and contact information, giving you peace of mind that they will be easily identifiable if they ever wander off. Please follow this format below and add it into the "customization details for nameplate" text box. (Nameplates can hold up to 3 lines of text, with a max of 15 characters per line) Line 1:Line 2:Line 3: (optional) 2-line engraving recommended for larger font sizeFont: Please keep in mind the added nameplate will take away about 1" off our standard sizing. We will make any necessary adjustments to our standard sizing based off the measurements provided to ensure a comfortable, secure fit. Please feel free to email us at [email protected] with any questions prior to ordering.