Hydraulic lifting mechanism: It uses a hydraulic pump system (often single or double piston) to raise the vehicle, reducing the physical effort required.
Low-profile / low minimum height: Many 4T trolley jacks are built for “low-clearance” vehicles — with a minimal saddle (lifting pad) height as low as ~ 75–140 mm, making it easier to slide under cars with low ground clearance.
Wheels / castors for mobility: Equipped with wheels (usually swivel castors plus fixed wheels) so you can roll the jack under the vehicle easily and reposition as needed.
Safety / overload protection features: Many models include a safety or overload valve to prevent lifting beyond rated capacity; some have controlled lowering mechanisms for safer descent.