None worked as well as this yagi antenna

The modem has a port for an external antenna and I found the antenna alone worked as well or better than the antenna with the booster for 3

HSPA+ in the cellular 850MHz band (as well as 2G 1xRTT and GSM in the 850MHz band).It will not work on LTE bands Band 2, 4, 10, 25, and 30

4G would only work on rare occasions and not too

One final tip is to use a small fan to keep your phone cool - between the Sleek 4g putting out heat and running a hotspot you can cook a phone on a warm day, so we use a small 5" USB fan pointed at the phone to keep it from overheating