You'd think they're just like any other one-inch ball. You'll know they aren't the instant you bang them together. Keep one in your hand. Throw the other. Once they touch, "bang," you hear a blasting sound you won't soon forget. Naturally, they come two per package. They're non-flammable, non-toxic and can be "banged" more than 400 times. Ear plugs are not included.