yea i think that item on amazon is snake oil as the old saying goes the 2 products i have purchased myself that i find to work are there's 2 first the
Bolo Brands N Wireless 18dbi 2.4GHz Wifi High Gain Antenna 18 dB 2.4
Link:http://www.amazon.com/Brands-Wireless-2-4GHz-Antenna-Booster/dp/B0054MLMLA?ie=UTF8&keywords=alfa%20wireless&qid=1464147889&ref_=sr_1_18&sr=8-18
if you need something more compact i would recommend
Alfa 9dBi WiFi Booster SMA OMNI-Directional High-Gain Screw-On Swivel Antenna
link:http://www.amazon.com/dp/B0039ORBLK?psc=1
don't think you will get a half mile out of it there's a few other products i've seen here and there on amazon that rock some asskicking DBi power that i have not gotten to play with yet
hope this post helps