A pair of tiny PCBs that get soldered underneath the CIA 6526A chips in Commodore computers. They contain ESD protection diodes that provide a better path for static shocks to travel which doesn't go right into the chips to blow them out. If the CIAs are socketed they go right between the socket and the chip. If they're not you'll have to desolder them (and you may as well install sockets while you're at it). Short, only 5mm high.
Solder this tiny board to the contacts of the joystick ports on your Commodore (supports the C64, C128, and Amigas; generally anything Commodore) and it'll prevent static damage to ICs on the mainboard through the joystick port by wicking away the current to TVS (transient voltage suppressor) diodes because they present an easier path to follow. Protects the CIA 6526A and 6581 chips in particular because there are relatively short routes from the jacks to those ICs.
This is a simple PCB that takes a SOT-23-6 TVS diode package to provide ESD protection on your Commodore 64 or Amiga with Atari style DB9 joystick ports. Install by soldering over the existing DB9 connector footprint on the back of your computer mainboard.
0.6mm thick PCB's with nice beefy traces. Available as a pair of bare PCB's or assembled with LiteON L13ESDL5V0C6-4 TVS diodes. If choosing your own TVS diodes, look for ones with a 5V standoff voltage (since the joystick ports signal levels are 5V). Many suitable parts may start or have SRV05-4 in their part number.