What a great system. The Boss has plenty of features easily accessible and has a range of 1 and a half kms - The Boss is built tough and offers 100 levels of blunt stimulation, plus a warning or tone (interchangeable). One of the favoured features is the ability to lock in a level that works for your dog, so if you knock or fiddle with the transmitter, you cannot accidentally use a level that maybe too high. Of course it is fully waterproof (transmitter floats) and shockproof. The E-Collar technologies brand is reported to offer the fasted response from transmitter to collar. There are other sophisticated features, including the ability to locate a lost transmitter - check out the features on the Collarton website.
Like any electronic system these are useful training tools and should be used alongside good training methods to back up your command instantly at a level that suits your dog and the issue at hand. The quick response allows your dog to understand why the correction is being made.