This is the new 3 Speed Throttle, it will not work on old models with a single speed. In order to upgrade your trike to the 3 speeds, you need all 4 compatible parts as listed below.

MotoTec 48v 700w Folding Trike – 3 Speed Throttle With Key
MotoTec 48v 700w Folding Trike – 3 Speed Wire Harness 4 Connector
MotoTec 48v 700w Folding Trike – 3 Speed Left Controller V2
MotoTec 48v 700w Folding Trike – 3 Speed Right Controller V2