Quote: (Originally Posted by
Gill Envy)

I highly recommend using the shearwater HUD, it's a stand alone and is easily installed on the Copis. Many would argue that it counts as a secondary since it's got it's own battery and brain. I really like the one I have on my Pursuit Copis.
Define easily installed...keep in mind I am not mechanically inclined. But I just looked up the price, and it does seem like a nice way to get some PO2 meter redundancy on the COPIS.....