Each purchase includes the following: 1 N52 with Brass Keychain The magnet will detect any ferrous metal such as iron, cobalt, steel or nickel. Metals such as aluminum copper gold silver WILL NOT attract to magnet (except for clasps, which sometimes have steel springs inside). Anything that passes a magnet test (no reaction from the magnet) can be scrutinized further using other methods, such as doing an acid test. It pairs well with our Techneak testing solutions; using it first to eliminate or seperate large quantity of gold/steel-plated pieces from authentic pieces. The magnets are the perfect size, attached to a keychain loop where it is always convenient. The magnets also have several other uses such as fishing lures, hobbists, sticking keyring to fridge so it doesn't get misplaced, picking up fallen screws, etc. The magnet insert is rated at 10 lbs (as with all magnets, this rating depends on the magnet mating to a smooth, flat, unpainted steel surface). These magnets have an excellent feel and are very sensitive. The brass casing protects the magnet from chipping and breaking. Comes with a split ring for easy carrying, and a protective vinyl cap. Dimensions are: .5" diameter x 1.75" length 1/2" diameter split ring.