Features: Transmitters have over 120m transmission range with special encoded frequencies. A bright LED light on each transmitter, and each light has different color. Low battery power warning. 2.5mm socket for plugging illuminated swinger. Transmitters are operated by 1 23A 12V battery (not included). Four different colors LED on the receiver--red, yellow, green, blue, to match four different bite alarms or transmitters.   The receiver has over 120m reception range. The receiver is powered up by 3 AAA batteries (not included) and can receive antenna. Note: Always have the alarm switched off when replacing or changing batteries. Alkaline battery is recommended for maximum battery life. Change the battery immediately if one of the parts falls into the water. This unit is not waterproof but can withstand droplets of water(ex. Light rain). Take out the battery before storing it to ensure a longer life and durability for the battery. Specifications: Material: ABS & stainless steel Total weight: 1146g / 40.43oz Swinger length: 25.5cm / 10in Receiver size: 10 * 6.5& 65290;2.5cm / 3.94 * 2.56 * 0.98in (L * W * H) Alarm size: 11.5 * 4 * 4.5cm / 4.33 * 1.57 * 1.77in Package size: 34 * 22  * 6cm / 13.4 * 9.1 * 2.4in Package weight: 1256g / 44.29oz Package List: 4 * Swinger 4 * Alarm 1 * Receiver 1 * Manual(English)