The Alert Combo pack combines Ammonia Alert (1 card) and pH Alert® (1 card). Ammonia Alert and pH Alert are almost half the size of competing products. At 1.5" x 2.5", they are small, clear, and unobtrusive, so they won't detract from the view of your aquarium. Simply place Ammonia Alert and pH Alert visibly anywhere in the aquarium or filter. It’s that easy. No chemicals or test procedures are required.