The Compact Laser Deluxe was a powerful laser weapon that is extremely small though still quite noticeably sizable.
Its compact dimensions were proven as Captain Jack Harkness managed to store it away somewhere "you really don't wanna know" (presumably in his backside or genetiles), in case of emergencies. Its only known carrier is Jack Harkness and it is used by him to destroy both the robots Trin-e and Zu-Zana. (DW: Bad Wolf)