... .W./N.W.: 9.5/8.5KgsEM1816-5 Button Compass, Dia16mm, 0.9g Packing: 20Pcs/PackInner Box ... Inner Boxes/CtnG.W./N.W.: 9/8KgsEM1817-B Button Compass, Dia17mm, 1.1g Magnetic Induction: 500 GaussPacking ... loosen three screws(3)change battery.4. Reflector: Call for help in countryside, reflect sunlight to sent ... data at horizontal and vertical level)7. Whistle: Call for help in countryside, sent out the sound ...