There are two main styles of transmitters for radio controlled vehicles. The pistol-grip style looks like a gun with a trigger and a knob. The stick-controller is box-like with two joysticks, knobs, or buttons, and additional switches.
The transmitter is also described by the number of actions (speed, movement, etc.) or channels it controls.
Remote controlled vehicles may have wired transmitters. A wire or tether connects to the vehicle (or to the track in the case of slot cars) and transmits signals to control the vehicle.
Crystals on Transmitters
On hobby-grade transmitters there is a slot for inserting one of a matching pair of crystals. The other crystal is inserted in the receiver inside the vehicle. The crystals set the radio frequency at which the transmitter and vehicle communicate. In the transmitter for a toy-grade RC, the crystal is usually soldered directly to the circuit board inside the transmitter.