Place dog's front paws through the left side opening, then place right paw through. Grab both D-rings on either side of the dog and lift the harness up so the chest strap rests against the dogs chest. Grab the plastic squeeze buckle and click. Make sure the two D-rings are in the center of the back. Use the slide adjusters to increase or decrease the size of the harness. Allow a finger's width of space between all straps and the dog. For use with a leash, attach the leash clasp through both D-rings. This item is not suitable for children. This harness is intended for pets only. Always supervise your pet when using this product. Inspect product for damage and discard if any part becomes loose or detached. If item becoms wet, some color transfer may occur. Please use caution around light colored upholstery or carpeting. Spot clean only.