Dogtra ARC Remote Training Collar System, Black Slim design receiver/collar ergonomically shaped to your dog's neck. The Dogtra ARC e-collar features a -mile range. Nick' and 'Constant' stimulation along with a non-stimulating pager/vibration Checkered grips on the handheld transmitter for a positive feel Rheostat/volume dial with up to 127 levels for a gradual adjustment in stimulation intensity User expandable to a two-dog system