The STANLEY? 10-778 FATMAX? retractable knife comes with 5 FATMAX blades and has an instant blade change mechanism. Features: Blade storage for 5 blades inside handle, Cartridge holds up to 5 blades, Comes supplied with 5 FatMax blades, Ergonomic design ideal for cutting material such as carpet without scrapping knuckles, Drop testing ensures knife still operates even if dropped, Interlock nose locking system for greater safety during cutting, Instant change button for fast blade changes, Narrow nose ideal for more accurate cutting applications, Soft touch panels for more comfortable grip, Solvent resistance ensures resistance to: Gasoline, Turpentine, Lacquer, Alcohol, Thinners, Mineral Spirits.