The KISS rebreather is a unit manufactured in Canada by Gordon and Kim Smith. This unit uses the philosophy to keep everything as simple as possible with maintenance of the unit remaining in the hands of the owner/diver.
It includes no electronics that can serve as points of failure. It does include three redundant and independent, oxygen sensors, each with its own ambient pressure cable.
The gas delivery system is as simple as you can get. There is a constant flow delivery through an orifice for the O2 side. This is adjustable to match closely to your metabolic rate. As the depth increases, the oxygen flow rate decreases due to the increasing ambient pressure and at the same time the rate of change of the PO2 slows due to the increased gas density. There is a manual add button to keep your PO2 right where you want it.
There is a pressure relief valve to protect the loop and users lungs from over pressurization and a tilt valve built into the head of the scrubber unit to deliver diluent if the lungs should bottom out during descent, the three sensors are all individually wired to their respective display with independent batteries for each display providing total redundancy. The sensors are easily accessible for replacement or testing, and the counterlungs are tucked into the case behind you. The difference in work of breathing is negligible, and only when you flip over on your back, will you get chipmunk cheeks. This as we see it, is the only significant difference between the KISS lungs and over the shoulder lungs. The advantage is a clear and uncluttered chest area and the lungs are protected inside the case, which are available in 4 and 6 Liter capacity.
This is a unit that almost flies by itself with just enough intervention by the user for total control. There is no solenoid to jam or fail and the electronics are the three independent digital displays. This rebreather is compact and well balanced for a better feel, and is adjustable to meet all diving trim requirements. The design is one that is very functional and smart.