[FCC APPROVED & RELIABLE SERVICE GUARANTEE] The cell phone boosters are FCC approved, and we offter 30-day money back, 3-month replacement and 5-year manufacturer warranty. [LARGE COVERAGE] The high gain directional outside yagi antenna focuses receiving signals in a particular direction and provides up to 4,500 square feet coverage, the more bars signal you get outside, the more coverage you get inside. If you only get 1 bar signal outside, you can choose it. [ADVANCED FEATURES KEEP STABLE SIGNAL] The booster is built in ALC detecting the existing signal strength and automatically adjusting itself for best performance, it prevents inconvenient shutdowns and downtime that keep you from doing what you need to do. [ANNTLENT APP HELP YOU INSTALL EASILY] No drills necessary while using the window entry cable route the cable from outside to inside. ANNTLENT APP helps you find the direction of the closest cell tower, so you can aim the outside antenna easily. [SUPPORTS ALL CARRIERS] Our booster enhances LTE and 5G signals for All Carriers on band 5, 12, 13 and 17, such as Verizon, AT&T and T-Mobile. Please CHECK YOUR BAND BEFORE PURCHASE and ensure that the frequency of your phone is band 5,12,13 or 17.