Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Proprietary Battery Required

The battery only worked from June 3rd to July 4th. One Month! That's when I discovered that the collar ONLY takes PetSafe's, DISPOSABLE, proprietary, RFA-67 battery. The sales description makes it sound like PetSafe is throwing in a free battery with the new collar but doesn't explain that, unlike my other UL-275 receivers; the collar can't use standard lithium batteries from Wal*mart or K-mart. You have to buy PetSafe's battery if you want it to work for another month!