13-6 Change A U.S. Navy Diving Manual—Volume 3 deep  as  950  fsw.  With  the  exception  of  the  demand  regulator,  it  is  functionally identical to the UBA MK 21 MOD 1, which is used for air and mixed gas diving. The regulator for the MK 21 MOD 0 helmet is the Ultraflow 500, which provides improved breathing resistance and gas flow over the MK 21 MOD 1. The  UBA  MK  22  MOD  0  is  an  open  circuit,  demand-regulated,  band-mask version of the UBA MK 21 MOD 0. It is used for the standby diver for saturation, mixed  gas  diving  at  depths  in  excess  of  300  fsw  and  as  deep  as  950  fsw.  It  is provided  with a hood and  head harness  instead of  the helmet shell  to present a smaller profile for storage. 13-3.8 Operational Characteristics.   Equipment operational characteristics are reviewed in Table 13-2 and specific equipment information can be found in paragraph 13-8. All  diving  equipment  must  be  certified  or  authorized  for  Navy  use.  Authorized equipment is listed in the NAVSEA/00C Authorized for Navy Use (ANU) list. For proper operation and maintenance of U.S. Navy approved diving equipment, refer to the appropriate equipment operation and maintenance manual. 13-3.9 Support Equipment and ROVs.   In addition to the UBA, support equipment must not  be  overlooked.  Items  commonly  used  include  tools,  underwater  lighting, power sources, and communications systems. The Coordinated Shipboard Allow- ance  List  (COSAL)  for  the  diving  platform  is  a  reliable  source  of  support equipment. Commercial resources may also be available. Table 13-3.  Mixed Mixed gasGas Diving Equipment. Type Principal Applications Minimum Personnel Advantages Disadvantages Restrictions and Depth Limits MK 21 MOD 1 EXO BR MS (Notes 1 & 3) Deep search, inspection and repair. 12 (Note 3) Horizontal mobility. Voice communications. Support craft required. High rate of gas consumption. Normal 300 fsw. Maximum: 380 fsw with CNO authorization. MK 21 MOD 0 (Note 2) Saturation diving search, salvage, and repair. Extensive bottom time. 21 (7 per watch) (Note 4) Maximum diver safety. Bottom time efficiency. Maximum comfort. Continuous personnel monitoring. Slow deployment. Large support craft and crew. Limited mobility. High rate of gas consumption. Varies with DDS certification MK 22 MOD 0 (Note 2) Standby diver for PTC. 21 (7 per watch) (Note 4) Collapsible for storage in PTC. Slow deployment. Large support craft and crew. Limited mobility. High rate of gas consumption. Varies with DDS certification Notes: 1. surface supplied deep-sea 2. Saturation UBA 3. Minimum personnel consists of topside support and one diver in the water 4. Varies according to manning requirements of deep dive system