At only 0.65” wide by 0.75” tall, the Aion Micro 3PDT Bypass is the smallest bypass wiring PCB available, only barely larger than a 3PDT stomp switch. This makes it perfect even for micro 1590A projects!
Wiring is dead simple: the pads labels match up to most legacy Aion PCB projects, so you can run the wires straight across and be done with it. The Refractor is the only PCB that is not compatible, and it has its own bypass PCB that can be used.
Refer to the PDF documentation for a wiring diagram along with a description of each of the connections if you want to use this for non-Aion PCBs.
Note that the newer 125B-series PCBs (2018-present) include bypass boards integrated as snap-off sub-PCBs. The micro 3PDT bypass boards are not needed with them.