Sturdy, utilitarian mono switched 1/8" (3.5mm) jack
For those who don't know, this is the same thing as a panel mount mono switched 1/8" (3.5mm) jack; Small Bear also sells (though at time it's out of stock) an open-frame version, with the SKU JCK300632E, that serves the same function. They're a bit pricey at a buck a piece, but they're pretty reliable for what they are.