Our Bayard Alpert, G100KF ionization gauge is a 1" kovar tubulation, single coated iridium filament gauge with a 2 3/4" flange. Our iridium filament gauge is your best choice in an oxygen rich environment and can even tolerate brief exposure to atmosphere when hot. Our gauges are most accurate continuous indicators for pressures below 1 x 10-3 Torr.