Magnetic levitation technology is important because it reduces energy consumption, largely obviating friction. Jamming or a Faraday cage may also work, the latter obviating removal of the battery. Obviating the second operation results in a lower unit cost and thus a lower price. Many detractors denounced both, obviating the distinction, while many advocates endorsed both. That could be achieved with front-wheel drive obviating the need for a central driveshaft. A single size can be used for infants, obviating any sizing errors. Later machines were supplied with caterpillar tracks, obviating the need for rails. No release agent is required, obviating post-production cleanup. For some equipment, break-in is now done at the factory, obviating end-user break-in.