This is a adapter for the sind-winder Speedloader for filling the Begadi spring grenade fast.
https://www.begadi.com/airsoft-granaten/begadi-airsoft-federdruck-granate-mit-integrierter-sicherung-einstellbarer-empfindlichkeit-robustes-design-einfach-bedienbar-fasst-bis-zu-300-bbs-tan.html
