Dogtra 640C Training CollarThe 640C is an ultra compact system that packs all the features of larger Dogtra collars but is designed for small to medium sized dogs. Activity: Obedience Power: Low to medium power stimulation Range: Up to 600 metres Weight: For dogs as small as 10 lbs Features Ultra compact receiver collar designed for smaller dogs Checkered grips on the handheld transmitter Nick and Constant stimulation along with the High Performance Pager Enhanced contact