We have the Garmin rhinos. We went with the 530 series, and they have a TON of features. The biggest reason we chose that product was the ability to 'pole' the positions of others in our group. We chose the 500 level because of the transmit wattage is much higher than the 100 series (I believe the 100 series is at 2 or 3 watts). But, even at the higher, 5-watt level, it's amazing just how short the communication distance can be! theres' no substitute for common sense, and paying attention!