This slip-on watering base is to be used with a plastic quart jar or mason quart jar. It is best used for baby chicks from 1-14 days of age. It does not screw on the jar but rather slips on and the suction seals the water when tipped over for operation as a waterer. It is stable but not as stable as the screw on type that is also offered by Cackle Hatchery®. However, it is very easy and fast to change out with water. Generally you would want about 1 of these to every 20 baby chicks and of course, you would need to refill as soon as they run out of water.