Options shown include corded power, battery-powered units (including devices that use AA batteries and some with non-removable batteries), and rechargeable units that use a docking station.
They are made for 3 x 5 inch index cards and are described as holding up to 250 cards.
Emery boards have two surfaces: a coarser side for shaping and a finer side for smoothing.
They use steel mesh construction with an open-top design for easy access, integrated carrying handles, and internal rails that let you hang files for added organization.
Descriptions list a fast charge (fully charged in about 1 hour), up to six hours of use on a full charge, and the ability to use the device while it is charging.