Some have timers that shut the water off automatically. Or you can select a sprinkler head that delivers fertilizer. Just fill it with a liquid or a water-soluble fertilizer and feed your lawn or garden while you water. Use the rose to supply a gentle shower to seedlings, or deliver a stream of water by removing the attachment. Plastic cans are lighter in weight and last a long time.
Metal cans look good but are heavy to lug around.
When you're choosing one, remember that each gallon of water weighs 8 pounds, so a full 2-gallon sprayer will weigh 16 pounds. On the other hand, a larger sprayer can cover a larger area without needing a refill.