A standard four-wheeled walker is the one most people are familiar with; it has two wheels on the front legs and none on the back. A rollator walker is a walker that features four wheels - one at the bottom of each leg. Rollator walkers will also have brakes that push down to lock. Rollator walkers are best for those who like rest breaks and need a bit of stability but can generally walk quite well. People with low endurance or lung conditions that leave them short of breath tend to opt for rollator walkers over the more traditional type.