One PSRAM chip 8MB (Use two on Teensybat detector!)
This is the PSRAM chip you can solder to the Teensy4.1 board. On the TeensyBat we use two if these to create an audiobuffer.
The audiobuffer allows us to store several seconds of audio that just passed allready. If you see or hear something interesting simply press record. Recording will start but you also store the past four seconds.
In the construction manual you can see this part is optional, but this is such a great feature that it is very much recommend to install two of these chips.