The SportDOG Brand FieldTrainer 425XS is our smallest and lightest e-collar built for in-the-field training or hunting with close working dogs. This 'S' model (SD-425XS) was built for high-drive, more stubborn dogs by offering a higher static stimulation range than the 425X. Consistency and perfect timing are critical to developing your sporting dog, so the remote is quickly and easily operated without having to look at it - which lets you focus on your dog and not your equipment. With only a slight movement of the dial and 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 purchase of Add-A-Dog; collars) out to 500 yards with any of the 425 models.