Adjusting Your Martingale

Using the metal slider loosen the collar to fit over your dogs head.
Slip the collar over your dog's head and slide it up to the narrowest part of the neck (just behind the ears).
Pull on the D-ring. The two metal slides should come together, but never touch, approx leaving a gap of two inches. tighten the slider to adjust the fit.
Maintain a two-finger width distance between the slides.
Check your collar periodically to ensure it is properly adjusted.