4500 EDGE for 1 Dog = 1 Transmitter + 1 Collar. 4503 EDGE for 3 Dog = 1 Transmitter + 3 Collars. 4502 EDGE for 2 dogs = 1 transmitter + 2 collars. 4504 EDGE for 4 dogs = 1 transmitter + 4 collars. (4502, 4503, 4504 ASC).
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