The present invention relates to an activator (90; 200; 300; 400) for a medicament delivery device, comprising a manually operable activator element (100, 204, 304; 416); an activator blocker (88; 208; 302; 402) operably arranged to said activator element (100, 204, 304; 416), said activator blocker (88; 208; 302; 402) defining at least one locking member (82; 216; 312; 426); a medicament delivery device housing comprising at least one flexible hook (65), wherein the at least one flexible hook (65) of the medicament delivery device housing is operably between a locked position where the flexible hook (65) is releasably engaged with the at least one locking member (82; 216; 312; 426) of the activator blocker (88; 208; 302; 402), thereby preventing operation of said activator element (100, 204, 304; 416); and an unlocked position where the flexible hook (65) is out of engagement with the at least one locking member (82; 216; 312; 426) of the activator blocker (88; 208; 302; 402), thereby allowing operation of said activator element (100, 204, 304; 416).本發明有關用於藥物輸送裝置的啟動器(90;200;300;400),包含可手動操作之啟動器元件(100、204、304;416);啟動器阻斷件(88;208;302;402),可操作地配置至該啟動器元件(100、204、304;416),該啟動器阻斷件(88;208;302;402)界定至少一鎖定構件(82;216;312;426);藥物輸送裝置外殼,包含至少一撓性鉤子(65),其中該藥物輸送裝置外殼的至少一撓性鉤子(65)係可操作於鎖定位置及開啟位置之間,在該鎖定位置,該撓性鉤子(65)係與該啟動器阻斷件(88;208;302;402)的至少一鎖定構件(82;216;312;426)可釋放地嚙合,藉此防止該啟動器元件(100、204、304;416)之操作;及在該開啟位置,該撓性鉤子(65)係不再與該啟動器阻斷件(88;208;302;402)的至少一鎖定構件(82;216;312;426)嚙合,藉此允許該啟動器元件(100、204、304;416)之操作。