How to choose the correct size harness? 1. Please measure your dog’s neck and chest circumference before purchasing. 2. Please allow 0.5-1 inch error due to manual measurement. 3.Here is the harness size guide for your reference: XXS - Neck Circumference (10- 12 inches), chest circumference (13-17 inches) XS - Neck (11-14 inches), Chest (16-18 inches) S — Neck (14-18 inches), Chest circumference (17-21 inches) M — Neck circumference ( 17-25 inches), Chest circumference (21-29 inches) L - - Neck circumference (21-31 inches), Bust (25-37 inches) Seat Belt: 20.87 inches - 29.13 inches x 0.98 inches (Length x Width) ? Why Choose Dog Car Harness Plus Connector Leash? 1. The harness leash is designed to be universally compatible with most standard vehicles while keeping your pet securely in place for safe travel. 2. This multifunctional harness belt can not only combine pleasure and pleasure during travel, but also can be combined with the retractable dog leash. Specifications: