Cis-Lunar was a firm that made computer-controlled closed-circuit automatic rebreathers for scuba diving. Some of its production models were in a streamlined casing. The firm's first plan was to develop spacesuit kit. The dot com crash in early 2000 prevented Cis-Lunar from financing mass production of the MK5 rebreather. The MK5 included design elements aimed at preventing system and mission failures.