Einstein Dog Training Collars are one of our newest product lines as Einstein is a fairly new company. Don’t let the fact that they are new dissuade you; on the contrary Einstein is out to make very safe products with the lowest levels of stimulation possible while still functioning as an effective dog training device. Currently every model that Einstein makes is fully rechargeable which is so much better than having to change out batteries. Just charge it after a couple training sessions and then you’ll never be postponing it to run to pick up fresh batteries.