Laser Wheel Alignment Gauge.
Here's some information for shopping:
It's an optical system using a low-radiation laser beam to indicate toe-in or toe-out.
It has a single leg configuration and reversible contact probes, allowing for on-ramp use.
It works on most cars and light commercial vehicles with rim diameters from 200mm (8") to 600mm (23.5").
It's powered by 2 x AA batteries and includes operating instructions.