The dual alert pack combines the ammonia alert (one card) and the pH alert® (one card). The ammonia alert and pH alert are approximately half the size of competing products. Measuring 1.5" × 2.5", they are small, clear, and unobtrusive, so they won't obstruct the view of your aquariums. Simply place the ammonia alert and pH alert clearly anywhere in the aquarium or filter. It's that easy. No chemicals or testing procedures are required.