The PetSafe 3-Volt Lithium Batteries (2-Pack) can be used with any battery-controlled PetSafe radio system, receiver or bark-control collar that uses lithium batteries. These long-lasting batteries are helpful to have on hand for fast battery replacement. Can be used with devices for dogs of all sizes. Compatible with the radio systems UL-275 and UL-250 receivers. Lithium batteries are long lasting. Each package contains two 3-Volt batteries.