Just Put The Collar Around Your Dog’S Neck And Adjust Itthen Leave The Collar On Your Dog Continuously For One Month (Except During Shampooing And Swimming In Swimming Pools) One Collar Provides 4 Weeks Constant Supportsmall Size Collar Fits Neck Up To 37.5 Cm, For Dogs Up To Approximately 15 Kglarge Size Collar Fits Neck Up To 62.5 Cm, For Dogs Up To Approximately 50 Kg