The Tri Tronics Flyway G2 EXP electronic dog training collar has the same features as the Flyway G2, but has the added feature of being user expandable up to 3 collars. It has 6 levels of continuous and 18 levels of momentary stimulation to make it easy for you to find the type and level of stimulation that works best for your dog. With the dial set on "A" you can remotely operate the Tri Tronics beeper or an future accessories that Tri Tronics may add. This Remote Trainer is designed to be simple so you can operate it without looking at the transmitter – watch your dog and deliver the appropriate stimulation at exactly the right time. Its designed with a no-slip grip so you don't lose it if it gets wet. The transmitter is waterproof and is made of Lexan. Lexan is the same material that is used in bullet proof products. The small, rugged, and waterproof dog training shock collar has insulated contact points that provide consistent and reliable stimulation in all training situations. It works reliably at one-half mile for long-range control over your dog. The receiver is 1/3 smaller than older models. It’s also made of the same tough Lexan material as the transmitter. It has a removable, waterproof battery pack and a battery life indicator. The receiver features an extra loop to keep it snug to the collar strap. Tri-Tronics field expandability feature makes it possible for you to expand your one-dog Remote Trainer into a multi-dog Remote Trainer by yourself. You can have a multi-dog Remote Trainer when you need one without placing a special order and the delay of having something built for your system at the factory. It is also easy to replace a lost collar if necessary right in the field. All collar straps are included with your original purchase, simply purchase additional EXP receivers to add up to 3 dogs. The new cradle charging system keeps your receiver and transmitter batteries in better condition than any previous charging system we’ve used. The charger charges rapidly – only two hours are needed. NiMH batteries do not have a “memory” so you can recharge at any time, even if the batteries have not run down. Also, you can leave the unit (or battery pack only) on charge in the cradle at all times when it is not in use without damage to the batteries. Tri Tronics Flyway G2 EXP Dog Training Collar features: Field expandable up to 3 dogs 18 levels of momentary and 6 levels of continuous stimulation 1-mile range Waterproof Battery indicator light 2-hour charging Cradle charging system Battery indicator light on both the transmitter and receiver Trickle charge - leave your unit on charge indefinitely Ability to operate a Tri-Tronics Beeper Removable battery packs No-slip grip on transmitter On/off collar switch Rugged antenna Long and short contact points provided 2 year warranty