Why not SPG under the left arm to left Chest D ring?

[The Chairman]

How often does a mechanical spg fails vs electronic?

If you include the accouterments needed for a B&G SPG, then about the same.

I thought I had an AI failure on a cave dive once. Then I realized I had scavenged that one off of that reg for my rec setup. No, never got into the cave, but I certainly felt foolish. My buddy sure razzed me for it too. Then we are back by the Bat cave in Ginnie and clumsy fingers, loses control of his right side tank and it crashes to the bottom where the bubbles from the broken hose gave us quite a scare and a nice silt out. I swam upstream and out of the cloud of bubbles and silt, and tugged on his fin to let him know I was there. Tank back in place, he joined me and I pointed at him and put my hand over my reg and to signal I was laughing at him. Once he gave me the middle finger salute, the silt out was down enough to swim out without holding onto the line. He never would tell me how he dropped his tank. He stopped teasing about my forgotten transmitter as well.

While any piece of equipment can fail at any time, it's usually the grey stuff behind the mask that's most apt to fail at the worst possible moment.

 

[Landlocked123]

so today I tested it out and it was definitely just a glance down to read pressure. Those house was not less streamlined and I did two 1.5 hour shallow dives and that i can tell its just as functional as the left waist D ring. I may opt for a smaller SPG if I stick to the Chest D ring .. both methods work well that i can tell. Tomorrow I may try the over the shoulder

 

[60plus]

My BCD (Aqualung Axiom) has a D ring just forward of my left kidney. I clip my SPG hose there. I just have to give it a slight nudge with my hand to read it and it never seems too get caught on anything.