JFET input in a TO-99 can — what you're getting
The PM356J is a single JFET-input operational amplifier in a TO-99-8 hermetic metal can package. The JFET front end delivers a 30 nA input bias current and a 1 mV typical input offset voltage, which keeps the DC error low in precision integrators and sample-and-hold stages. The 4.5 MHz gain-bandwidth product paired with a 12 V/µs slew rate means it can swing a 10 V peak-to-peak output up to about 190 kHz before the slew rate limits the full-power bandwidth — useful for fast analog signal chains in test equipment or audio processing.
44 V supply span — dual-rail or single-rail flexibility
That covers the common ±15 V industrial rails with headroom to spare. The 5 mA supply current is moderate — not a micropower part, but reasonable for a general-purpose JFET op-amp in a metal can where the package itself acts as a shield against radiated pickup.
It belongs inside a benchtop instrument, an audio mixer, or a lab power supply — not in an engine bay or an outdoor telecom cabinet. The TO-99 metal can helps with thermal conductivity to the board, but the silicon itself is not specified below freezing.
If you are qualifying a BOM line, this part does not need a second-source override for lifecycle reasons alone.