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.