No hammer should be used in installation .Noexcessive force should be applied lest the device be damaged A device powered by solar energy ,making use of ultrasonic waves to repel harmful rodents Would never hurt your pets and plant or children .the sonic pulses are designed for moles ,voles ,gophers .shrews and other burrowing rodents ,as well as snakes and other pests like locusts and flies . to be better protect garden ,lawn and field from pest No need to take care of it that after 4 hours charging in full sunlight develops a full solar charge which should last for 5 days