Type a : Model Number : jyt-850 a Cdma:850 to894MHz gsm:925-960MHz Dcs: 1,805 -1990MHz 3g: 2,110 -2,170MHz Wi-Fi: 2,400 -2,500MHz Gps:1570-1580(gpsl1) 4g wimax:2345-2400MHz or 2620-2690 mhz 4g lte:725-770mhz Total output : 4 watt Shielding range : 10-20 m Type b : Model Number : jyt-850 b Gsm:850 to960 MHz Dcs: 1,805 - 1990MHz 3g: 2,110 - 2,170MHz Wi-Fi: 2,400 -2,500MHz Gps:1570-1580(gpsl1) 4g wimax:2345-2400MHz or 2620-2690 mhz 4g lte:725-770mhz Lojack : 160-175 mhz Total output : 4 watt Shielding range : 10-20 m This model has the most advantages: 1. With Dip switch so can make you easy to take on and off any bands you want . 2. Good cooling system with 2 cooling fans inside 3. Work non-stopped 4. Stable capability 5. Could be used in car directly,With car charger (Option) 6. It is the first biggest 4 watt portable cellphone jammer in market