These are usually ball bearings, although some headsets use needle bearings.
Roller Hockey International | roller coaster | Crestone Needle | needle | The Roller Blade Seven | wooden roller coaster | Roller Derby World Cup | Cleopatra's Needle | Sewing needle | Team Australia (roller derby) | Roller-compacted concrete | Roller chain | Return of the Roller Blade Seven | Providence Steam Roller | Needle in a Slunk Stack | Major League Roller Hockey | Loch Ness Monster (roller coaster) | Hello Kitty: Roller Rescue | Gotham Girls Roller Derby | Boomerang (roller coaster) | yaw bearing | USA Roller Sports | Titan (roller coaster) | The Beast (roller coaster) | steel roller coaster | Slewing bearing | S.L. Benfica (roller hockey) | Roller skiing | Roller rink | roller rink |