Comments about Manta Manta Pony Pressure Gauge:
Reliable. Easy to read, even with its small size, thanks to the color codes. Great addition to any front mounted pony or stage bottle. For back mounted pony I'd suggest a normal, hose mounted SPG, but for a tank that you will handle at the front, the small size and direct mounting to 1st stage becomes an asset. Handles Nitrox up to 40%O2 with no problems. I haven't used it with higher concentrations or Trimix.