LOPURS GSM 800 Cellular Phone Signal Repeater Booster + Antenna (Coverage: 100 Square Meters) Golden Attention please: this is for GSM 850 net band cellphones, not for GSM 1900 and CDMA 2000/2100! Up-link frequency: 824-849MHz,Coverage: approx. 50 square meters. Automatically adjusts power levels as needed to ensure a consistent coverage footprint Small regions signal blind or weak signal area, such as underground or semi-underground place of business, basements, underground parking, etc. Home, office, luxury yachts, private cars, public security system and road safety management