A Grapnel Launcher is an Imperial device that uses an explosive charge to fire a grapnel hook and its accompanying filament over long distances. A Grapnel Launcher is used to scale vast heights and cross from building to building in dense urban areas. It is a piece of equipment commonly employed by the close combat stealth assault Reiver Squads of the Primaris Space Marines, who always need to be in exactly the right place at exactly the right time, ready to burst forth from their stealthy approach and attack their foe when they least expect it.
- Codex Adeptus Astartes - Space Marines (8th Edition), pp. 71, 156