Fastest USB GSM Modem

I'm looking for the fastest USB GSM Modem that takes a sim card to get internet over the cell networks. I've seen 2g versions, and pretty sure they make 3g ones, what about 4g? Can anyone recommend one?

Go for this one, i guess

http://www.amazon.in/Verizon-Wireless-LTE-Modem-551L/dp/B0069RXK9G?tag=googinhydr18418-21