The base Optima CM does not include an oxygen cylinder, however they are available. Dive Rite recommends an aluminum 13 cf (2L) cylinder for on-board oxygen use. The diver may also choose to sling an oxygen bottle of their choosing separately for off-board use.
The on-board cylinder is held in place with two included adjustable cam straps. No additional cylinder mounting hardware is necessary.
The AL13 cylinder is a good compromise between weight and gas volume. It is an excellent choice for general rebreather diving. Other recommended cylinders that will work as on-board bottles with the Optima CM are:
- Aluminum 20 cf (3L)
- Steel AA LP13 cf (2L)
- Steel AA LP15 cf (2L)
- Steel AA LP27 cf (4L)
- Steel AA HP32 cf (4L)
However, the larger cylinders may have undesirable buoyancy characteristics when used as on board cylinders. Divers should select cylinders based on their dive duration, travel logistics, and buoyancy characteristics.