I now have bought 4 of these. They work great. I use two, and I have gotten chickens for my kids and installed one of these on their coops, and they love them also. Chickens will put themselves to bed, they just need someone (or thing) to shut the door, and open again in the morning, and this does the job. The batteries last surprising long (unfortunately, rechargeables do not last and do not have enough power - they are lower voltage than regular batteries), but lithium AAs work great, and last.