The R9 has 7 user-adjustable levels and a battery life of up to 2 years. Includes Status Light, AutoMemory® and TattleTale®. Works on all dogs. Usually used on dogs 15 lbs and larger. Kit includes an R9 receiver, 1 battery, 1 collar strap, 2 standard contact posts, and attachment accessories. Available Sizes:  ⅝" Collar Strap - Mini (6"-9"), XS (8"-11"), S (10"-13") ¾" Collar Strap - XS (8"-11"), S (10"-13"), M (12"-16"), L (14"-21") 1" Collar Strap - M (12"-16"), L (14"-21"), XL (19"-29")