The PRO 550 uses the tried and true tube-shaped design that trainers have come to love but is easy to operate (and master) 1-handed so you can keep your eyes on your dog at all times even while switching between stimulation levels and dogs. The stimulation level/vibrate selection dial is at the top of the transmitter allowing intuitive operation. Tone beacon lights and beeper are controlled using the switch and buttons on the face of the handheld unit. The control buttons comfortably line up in the hand for fingertip control. A 2 1/2-inch fixed transmitter antenna eliminates the threat of a lost or broken antenna while delivering up to 1 mile range.