Sportdog FieldTrainer 425X, Smallest & Lightest E-Collar, Built For In The Field Training Or Hunting With Close Working Dogs, Consistency & Perfect Timing Are Critical To Developing Your Sporting Dog, So The Remote Is Quickly & Easily Operated Without Having To Look At It, Which Lets You Focus On Your Dog & Not Your Equipment, With Only A Slight Movement Of The Dial & The Push Of A Button, You Will Be Able To Deliver A Tone, Vibration, Or One Of The 21 Levels Of Static Stimulation, Use These Stimulations To Communicate With Up To 3 Dogs, With Additional Add A Dog Collars, Not Included, Out To 500 YD With Any Of The 425 Models.