In-line shutoffs started in the rebreather world, but have since seen use by many divers on there stage bottles. This is a simple system that works great push the knob one way and you get gas push the knob the other way and no gas. It does not get any simpler than that. Safety Note: Use a over pressure relief on the First Stage One thing to always consider with inline shut offs is there is now no pressure relief on you’re your regulator. If you regulator has a high pressure seat creep you will still high build pressure in your hose. This pressure would normally be vented via your second stage. The problem now is that we have added an on/off valve there is no way for the pressure to escape. This leads to either a ruptured hose.