Businesses supplying navigational equipment provide devices and supporting materials that help people determine position, plan routes and travel safely. Depending on their specialism, they may serve recreational and commercial boat users, professional operators, walkers or vehicle users. Equipment can include satellite navigation units, electronic chartplotters, GPS receivers, compasses, radar, depth sounders, speed instruments, AIS units and autopilots. Customers may also find paper and digital charts, maps, route-planning software, antennas, mounting brackets, cables and other installation accessories. Some suppliers offer advice on choosing compatible equipment, fitting and configuring systems, updating software or chart data, and repairing or maintaining devices. Marine specialists may supply equipment designed to withstand water, salt and vibration, while other businesses focus on portable or vehicle-based navigation.