The Wilson Sleek is a good unit. It is only good for one device at a time. There are some slight variations in the Wilson Sleek line. 4G for all, 4G for AT&T, 4G for Verizon.
Depending on your distance to the booster the Wilson Mobile Pro 4g can be upto twice as powerful. It covers all 4G. It also can boost upto 4 devices at the same time. Distance to inside antenna is key. The closer the cellphone to inside antenna the stronger the signal.
On average:
Wilson Sleek 18db signal increase
Wilson Mobile Pro 4g - 35db with device on or next to inside antenna
- 5/10db increase with device at maximum range of 5ft
With the Mobile Pro 4g, place your mifi or cellphone next to the inside antenna. Then use Bluetooth or wifi for access.
Antennas can make a big difference. I use the supplied 4" rubber antenna. The small rubber antenna does little for/against the signal. Other antennas are good for 3g but negatively affect 4g. Vice versa.
Middle of the vehicle hood is usually a good place for the antenna.
Wilson Mobile Pro at Amazon